Petroleum Geology Acronyms

Acronym Glossary

3DEX 3D Induction Logging Service (BAKER ATLAS WIRELINE tool code)

A

A ampereA-h Ampere-hourAACT Aluminium Activation Clay Tool (SCHLUMBERGER)AAODC American Association of Oilwell Drilling ContractorsAAPG American Association of Petroleum GeologistsAASG AASG Association of American State GeologistsAAZD Apparent AzimuthABC Association of Boards of Certificationabd abandonedABS American Bureau of ShippingAC Acoustilog (BAKER ATLAS WIRELINE SERVICES)AC Alternating currentAC/CAL GR Acoustilog Caliper Gamma Ray (BAKER ATLAS WIRELINE SERVICES)AC/CAL NEU Acoustilog Caliper Neutron (BAKER ATLAS WIRELINE SERVICES)ac-ft acre-feet. 1 ac-ft = 7758 barrelsACCF Acceleration MagnitudeACCX X AccelerometerACCY Y AccelerometerACCZ Z Accelerometer and timeACOE Army Corps of EngineersACOP Adjusted Coefficient of PerformanceAC SIGN Acoustic SignatureACT Aluminum Clay Tool (SCHLUMBERGER TOOL)ACT Automatic Custody TransferACT Geochemical Logging Tool (SCHLUMBERGER TOOL)ACT(V) ActiveADN Azimuthal Density Neutron (MWD, SCHLUMBERGER TOOL)ADW Approval to Drill WellsAEC U. S. Atomic Energy CommissionAFDN Amplified Fluid DensityAFE authority for expenditureAGC Automatic gain controlAGI American Geological InstituteAGS Aluminium Gamma Ray Spectroscopy Sonde (Schlumberger)AGU American Geophysical UnionAHD Along Hole DepthAHF20 AIT-H 20 inch investigationAHF60 AIT-H 60 inch investigationAHF90 AIT-H 90 inch investigationAHFCO90 AIT-H 90 inch investigation conductivityAHO90 AIT-H 90 inch investigation (Schlumberger)AHO10 AIT-H 10 inch investigation (Schlumberger)AIAT MAI Array TemperatureAIBT Borehole Temperature RawAIIT MAI Internal TemperatureAIME American Institute of Mining, Metallurgical, and Petroleum Engineers (New York City - based parent group of the SPE).AIR1 Induction Receiver 1AIR2 Induction Receiver 2AIR3 Induction Receiver 3AIR4 Induction Receiver 4

AIS Array Induction SondeAIST MAI StatusAIT Array Induction Tool (Measures five depths of investigation, Schlumberger)AITC MAI Transmitter CurrentAIX1 Induction VX1AIX2 Induction VX2AIX3 Induction VX3AIX4 Induction VX4ALARA As Low As Reasonably AchievableALAT Azimuthal Laterolog (Schlumberger)AMNH American Museum of Natural HistoryAMPB Compensated Amplitude BiasAMS Auxiliary Measurement Sonde (Schlumberger)ANS Alaska North Slope (Acronym).ANSI American National Standards InstituteANSP Academy of Natural Sciences PhiladelphiaAOC Area Of ConcernAOF Absolute Open Flow.AOSC The Association of Oil Well Servicing Contractors (based in Dallas, sets some standards, principles, and policies of oil-well servicing contractors).AP Annular Pressure BAKER INTEQAPC Division of Air Pollution ControlAPI American Petroleum Institute (a national oil trade organization founded in 1920)API Oil gravity measurement unitAPOR Apparent PorosityAPS Accelerator Porosity Sonde (SCHLUMBERGER tool)APWD Annular Pressure While Drilling (MWD, Schlumberger)ARC Array Compensated Resistivity (MWD, Schlumberger)ARCHA Archie AARCHM Archie MARCO Atlantic Richfield CompanyAREF Azimuth of Pad 1ARI Azimuthal Resistivity Imager (SCHLUMBERGER tool)AS Associated substances (nonhydrocarbon gas, liquid, or solid compounds that are mixed or in chemical co9mbination with reservoir oil or gas)ASI Array Seismic Imager (SCHLUMBERGER tool)ASME America Society of Mechanical Engineers (set equipment standards that are sometimes used by oil industry)ASSE American Society of Safety Engineers (establishes sfety practices for several industries, based in Chicago).AST Aboveground Storage TankASTM American Society for Testing and Materials (set guidlines for the use of equipment and materials for oil fields, based in Philadelphia)ASTSWMO American State and Teritorial Solid Waste Mangement OrganizationASTSWMO Association of State and Territorial Solid Waste Management OfficialsAST Advanced Treatment SystemsAST Acoustic Scanning ToolASV Annular Safety ValveASZ Antelope Shale ZoneAT10, AT60, AT90 = Shallow, medium and deep resistivity logsATEN Signal Attenuation (between receivers)atm atmosphereATTN attenuationAU Assessment unit

AV Annular Velocity (Drilling)avg averageAVO Amplitude Variation with Offset (Geophysics)AVOL Annular VolumeAWO Approval for Well OperationsAWR Array Wave Resistivity/Gamma Ray (PATHFINDER LOGGING)AZ AzimuthAZAT Dip Azimuth from ASTAZBM Mean AzimuthAZBT Azimuth of Tool ASTAZIC Dip Azimuth (True North)AZID Borehole Azimuth

B

B 1) boron; 2) bottom of (drilling)B, bbl BarrelB/ Bottom ofB/D Barrels per dayBa bariumBADT Best Demonstrated Available TechnologyBAZI Borehole Azimuth (Magnetic)BAZT Borehole Azimuth (True)BB Billion barrelsbbl barrelBBL Billion barrels of petroleum liquids; includes crude oil, condensate, and natural gas liquidsBBNGL Billion barrels of natural gas liquidsBBO Billion barrels of crude oilBBOE Billion barrels of oil equivalentBCDC Corr. Deep Conductivity, MDLBCDL Corrected Deep Laterolog, MDLBCF,Bcf Billion cubic feetBCFG Billion cubic feet of natural gasBCMC Corr. Micro Conductivity, MDLBCML Corr. Micro Laterolog, MDLBCSC Corr. Shallow Conduct., MDLBCSL Corr. Shallow Laterolog, MDLBCS Borehole Compensated SonicBDC Bottom Dead CenterBEG Bureau of Economic Geology, University of Texas at AustinBELI Balcones Energy Library Inc.Best DT Automated sonic waveform processing for best slowness (Schlumberger)BFPH Barrels of Fluid Per Hour (used in drilling reports)BGL Below Ground LevelBGS Borehole Geometry SondeBHA Bottom Hole Assembly (toolstring on coiled tubing or drill pipe)BHC Borehole Compensated Sonic log, also called sonic logs, determine porosity by measuring how fast sound waves travel through rocks in the well. In general, sound waves travel faster through high-density shales than through lower-density sandstones.BHD Borehole DepthBHFL Borehole fluid type logBHP Bottom Hole PressureBHPT Borehole Properties ToolBHS Borehole statusBHT 1) Bottom Hole Temperature; 2) Borehole Temperature Raw CNSBHTD Differential TemperatureBHTF Borehole Temperature Log

BHTV Borehole Televiewer (Schlumberger)BHUN Paine Pressure (Abs) 100's MFTBIT Bit SizeBL Barrels of petroleum liquids; includes crude oil, condensate, and natural gas liquidsbld bailedBLM Bureau of Land ManagementBLPD Barrels of Liquid Per DayBNBT MBN Bulkhead Temperature MBNBNGR Gamma Ray Raw MBNBNIT MBN Internal Temperature MBNBNST MBN Status MBNBNFL British Nuclear Fuels LimitedBNGL Barrels of natural gas liquidsBNXA X Accelerometer MBNBNXM X Magnetometer MBNBNYA Y Accelerometer MBNBNYM Y Magnetometer MBNBNZA Z Accelerometer MBNBNZM Z Magnetometer MBNBO Barrels of crude oilBO Barrels of OilBOE Barrels of oil equivalentboed barrel of oil equivalent per dayBoi Oil FVF under reservoir conditions, Bbl/stbBONE Paine Pressure (Abs) 1's MFTBOP Blowout PreventersBOPD Barrels of oil per daybpd,BPD barrel per dayBPH Barrels Per HourBPV Back Pressure Valve (goes on the end of coiled tubing a drill pipe tool strings to prevent fluid flow in the wrong direction)Br bromineBRENT In Europe “Brent” is the reference quality of crude from the North Sea. Each market requires reference crudes to compare the prices of different quality products. It is used on both the Physical Market and the Spot Market.brkn brokenBRKT Breakout Angle PSDBscf Billion Standard Cubic FeetBSF Far Borehole Sigma TDSBSN Near Borehole Sigma TDSBRT Below Rotary Table (used a datum for depths in a well)BRT High Resolution TemperatureBS bit sizeBS&W basic sediment and waterBSAL Borehole salinityBscf/d Billion Standard Cubic Feet of gas per dayBSCO Borehole salinity correction optionBSP Bridle Spontaneous Potential (Schlumberger)BTEN Paine Pressure (Abs) 10's MFTBTHO Paine Pressure (Abs) 1000's MFTBTLF Filtered Borehole Tilt MBNBTLT Borehole Tilt MBNBTTH Paine Pressure (Abs) 10000's MFTBTU British Thermal UnitsBtu/lb British thermal units per poundBVH Buena Vista Hills oil fieldBVIL BULK VOLUME IRREDUCIBLE WATER FROM TIME DOMAIN (Halliburton)BVIMD MRIL BULK VOLUME IRREDUCIBLE FROM LONG Tw (Halliburton)BVW bulk volume waterBVWirr bulk volume water irreducible

BW Barrels of waterbwd barrel of water per day (often used in reference to oil production)BWPD Barrels of Water Per DayBWPH Barrels of Water Per HourBWR Boiling Water ReactorBZAC Z Accelerometer Counts MBNBZAT Z Accelerometer Time 1/10 millisecond MBN

C

C Celsius or degrees CentigradeC-NOPB Canada-Newfoundland Offshore Petroleum BoardCa calciumCA Corrective ActionCABX X Acoustic Caliper ASTCABY Y Acoustic Caliper ASTCACN Density Caliper Raw CDSCADF Microlog Caliper DLSCADP Density Caliper Raw PDScal calorieCAL Caliper MLS/MRSCAL2 Y Caliper Raw TACCALE Microlog Caliper Raw DLSCALI Generalized CaliperCALT Y Caliper TACCALX X CaliperCALY Y CaliperCAMR Micro-Resistivity Caliper MLS/MRSCANC Density Caliper CDSCAODC Canadian Association of Oil-Well Drilling Contractors (the Canadian counterpart of the IADC)CAPD Density Caliper PDSCAXR X Caliper Raw PSDCAYR Y Caliper Raw PSDCAD Computer-aided DesignCAL Caliper log (BAKER ATLAS WIRELINE SERVICES)CALI Caliber log (CA_, C_)CALM Catenary Anchor Leg MooringCAODC the Canadian Association of Oil-Well Drilling ContractorsCapex Capital ExpenditureCAPP Canadian Association of Petroleum ProducersCAST Circumferential Acoustic ScanningCB Core BitCBFC Cumberlant Belt-Flemish CapCBHT Circulating Bottomhole TemperatureCBIL Circumferential Borehole Imaging LogCBL cement bond longCBTT Combinable Borehole Televiewer Tool (Schlumber)CBVWE Bulk volume water effective (Halliburton)CCC Cross Connection ControlCCCO Casing & cement thickness correction optionCCL casing collar logCCLG Casing Collar Locator MCGCCLP CCL PRDCCLT CCL TDSCCN Caliper Corrected Neutron (BAKER INTEQ)CCO Conventional Crude OilCcw Clay-bound water conductivityCDL Compensated Density Log (HALLIBURTON)CDN Compensated Density Neutron (MWD, Schlumberger)

CDOGGR California Division of Oil, Gas and Geothermal Resources (=DOGGR)CDR Compensated Dual Resistivity (MWD, Schlumberger)CDS Compensated Density SondeCEAA Canadian Environmental Assessment Act.CERCLA Comprehensive Environmental Response Compensation and Liability ActCERCERI Center for Earthquake Research and Information, (formerly TEIC)CERT Corporate Emergency Response TeamCF Cubic feetCFG Cubic feet of natural gasCFGPD Cubic Feet of Gas Per DayCFPD Cubic Feet Per Daycfs cubic feet per secondCG Connection GasCGCL CCL Raw MCGCGD Compliance Guidance DocumentCGDT Downhole Tension MCGCGGR Gamma Ray Raw MCGCGIT MCG Internal Temperature MCGCGM Coarse Grid ModelCGSP SP Raw MCGCGR “uranium-free” measurement of NGSCGST MCG Status MCGCGVN Line Voltage (-ve) MCGCGVP Line Voltage (+ve) MCGCGVT Line Voltage MCGCGXT MCG External Temperature MCGCHDT Cased Hole Dynamics Tester (Schlumberger)chk chokeCHFR Cased Hole Formation Resistivity (Schlumberger)CHFT Cased Hole Dynamics Tester (Schlumberger)CHL ChlorinlogCHP Casing Hanger Pressure (pressure in an annulus as measured at the casing hanger)Ci CurieCI Compression IgnitionCIF Corporation Information FactoryCl chlorineCIL1 Conductivity Receiver 1 MAICIL1 Induction Channel 1 AISCIL2 Conductivity Receiver 2 MAICIL2 Induction Channel 2 AISCIL3 Conductivity Receiver 3 MAICIL3 Induction Channel 3 AISCIL4 Conductivity Receiver 4 MAICIL4 Induction Channel 4 AISCILD Deep ConductivityCILD Calibrated Induction Deep Conductivity (SCHLUMBERGER tool)CILM Medium ConductivityCILS Shallow ConductivitCIPA California Independent Petroleum Associationcirc circulatedCIU Currently In UseCL PPM Cloride ionCLDC Density Caliper MPDCLT Commercial Low TemperatureCLTC Two Arm Caliper MTC

CITHP Closed In Tubing Hanger Pressure (THP when the well is shut in)CLAM Crude Lift And Measurementcm CentimeterCMC Carboxymethyl CelluloseCMG Computer Modeling Group, Inc., Calgary, CanadaCMM Coalescence Microseismic Mapping (Schlumberger patented tech)CMP Common Midpoint. The assumption that a recorded seismic was reflected by a point midway (horizontally) between the source and detector.CMR Combinable Magnetic Resonance (Schlumberger)CMR2 Combinable Magnetic Resonance toolCMR-Plus Combinable Nuclear magnetic Resonance Plus (Schlumberger)CNC Nutron logCNCF Nutron porosity?CNCT Concatenated Data Channel MBDCNL/CN Compensated Neutron Log, also called neutron logs, determine porosity by assuming that the reservoir pore spaces are filled with either water or oil and then measuring the amount of hydrogen atoms (neutrons) in the pores. Because these logs underestimate the porosity of rocks that contain gas they result in "crossover" of the log curves when paired with FDC logs.CNPH Complete Net Pay ThicknessCNPHI Compensated Neutron PorosityCNS Compensated Neutron SondeCNSOPB The Canada-Nova Scotia Offshore Petroleum BoardCNT Compensated Neutron Tool (SCHLUMBERGER tool)CNTS Slim Compensated Neutron Tool (Schulumberger)CNWRA Center for Nuclear Waste Regulatory AnalysesCO Circulate OutCOB continent-ocean boundary.COE Corps of EngineersCOFR Continuous Flow Rate PRDCOLC Collar Detector Copy CCLCOLD Collar Detector CCLcomp completedCond. CondensateCOND conductivityCONF Filtered Conductivity PRDcongl conglomerate (drilling)COR Carbon/OxygenCORC Correlation Value PSDCOIP Current Oil In PlaceCOTS Customer Off The ShelfCORV Pipe Integrity (Schlumberger)COT cargo oil tankcp centipoiseCP Casing PressureCPA closest point of approachcpc Computerized Production ControlCPM Counts Per MinuteCPP Casing Potential Profile (Baker Atlas Wireline Services)CRAT dip correlation from ASTCRAT N/F Count Rate Ratio TDSCRC Core Research Center, U.S. Geological Surveycrd cored (drilling)GRDI Gamma Raycrg coring (drilling)CRPDN Gravel Pack Evaluation Density-Neutron (Schlumberger)CS Cable speed

CSIZ Current casing sizeCSNG Compensated Spectral Natural Gamma Ray (HALLIBURTON)CSP Clay smear potentialCSPG Canadian Society of Petroleum GeologistsCSS Compensated Sonic SondeCSS Cyclic Steam StimulationCSSO Contractor Supervisor Safety & Environmental OrientationCST Core Sample Taker; Chronological Sample Taker (Schlumberger)CSU Cyber Service unit (wellsite computer system for logging)CT Coiled Tubing Ct 1/Rt = true formation conductivityCTIE CLL Tie in Log CCLCum. CumulativeCUSEC Central United States Earthquake ConsortiumCw 1 /Rw, formation water conductivityCWEI Casing weightCWR Critical Well ResponseCWRT Critical Well Response Training

D

D Darcy or darciesd or D DayD, Den DensityD&A Dry and AbandonedD&C Drilling and CompletionsDAC Digital Array AcoustilogDAL Digital AcoustilogDAL2 Dielectric Log - 200 MhzDAL4 Dielectric Log - 47 MhzDAZ ?azimuthdB decibelDC 1) Direct Current; 2) Drill CollarDCAL (in)DCCP Density Caliper Raw MPDDCOR density correctionDCRF Far Density CountsDCRN Near Density CountsDCS distributed control systemDEN bulk densityDERL Denver Earth Resource LibraryDDLL Deep Laterolog MDLDDP Dialog Decision ProcessDDS Drillstring Dynamics SensorDECF Far TDS Decay TDSDECN Near TDS Decay TDSDECT Decay Integration Time TDSDEG Division of Environmental GeosciencesDEN Compensated Density MPDDEN Density DENF Far Spaced Density MPDDENN Near Spaced Density MPDDEST Deserted (well status)DF Derrick FloorDFCDFCL differential caliperDFD Drilling fluid densityDFL Deep Focused Log?DFO Department of Fisheries and OceansDGLL Groningen Laterolog MDLDGPS Differential Global Positioning System

DGR Dual Gamma Ray (Schlumberger)dh Borehole diameterDHC Density hole correctionDHSV Downhole Safety ValveDHT Down Hole Tension (HALLIBURTON)di Diameter of invasion.DI Deep inductionDIFC Differential C+C28aliperDIFL Dual Induction Focused LogDIL Dual Indiction Log (deep and medium depths of investigation, HALLIBURTON)DILL Invasion Depth MDLDIMS Downhole Information SystemDIPC Dip Angle PSDDISC DiscriminatorsDIP High Resolution 4-Arm DiplogDIR Directional (BAKER INTEQ)DIT Dual Induction Tool (SCHLUMBERGER tool)DL11 4' Discriminator Level MSSDL12 6' Discriminator Level MSSDL21 3' Discriminator Level MSSDL22 5' Discriminator Level MSSDLL Dual Laterolog (deep and medium depths of investigation), SCHLUMBERGER toolDLL Deep LaterologDLLI Deep Laterolog CurrentDLLT Dual Laterolog (HALLIBURTON)DLLV Deep Laterolog VoltageDLS Dual Laterolog SondeDLSC Shallow Current Check MDLDLSG Shallow Guard Current MDLDLSI Shallow Current MDLDLSP SP Voltage Raw MDLDLSV Shallow Voltage MDLDLT Dual Laterolog (Schlumberger)dm decimeterDM01,2,3 AST Diameter 1, 2, 3DMN DimensionDNFD Far Neutron Raw MDNDNFT Far Neutron Dead Time MDNDNIT MDN Internal Temperature MDNDNND Near Neutron Raw MDNDNNT Near Neutron Dead Time MDNDNST MDN Status MDNDO Depth offsetDOE 1) Department of Energy; 2) Design Of Experiment (reservoir engineering)DOE-O United States Department of Energy-Oversight Division (state agency)DOGGR Division of Oil, Gas and Geothermal Resources (California Depart of Conservation)DOI US Department of Interiordo, dol dolomiteDORL Depth offset repeat analysisDOSECC Drilling, Observation, and Sampling of the Earth’s Continental CrustDP 1) Deep resistivity; 2) Drill Pipe.DPA Drilling Program AuthorizationDPA Division of Professional Affairs, AAPGDPAT Dip Angle from ASTSPbl

DPHI Density Porosity logDPHISDPHZ Std. Res. Density PorosityDPIL Dual Phase Induction Log, BAKER ATLAS WIRELINEDPO density porosityDPORDPPM Density porosity processing modeDPOR Base Density Porosity MPDDPOR Limestone Density Porosity CDSDPOR Limestone Density Porosity PDSDPRD Dolomite Density Porosity MPDDPRD Dolomite Density Porosity CDSDPRD Dolomite Density Porosity PDSDPRL Limestone Density PorosityDPRS Sandstone Density PorosityDPRT Deep Propagation Resistivity (BAKER INTEQ)DPT Deep Propagation Log (Schlumberger)DRES Deep ResistivityDRESS Deep resistivityDRDP DPT Resistivity Mixed After Invasion, electrical resistivityDRG Digital Raster GraphicsDRHO Density correction (G/C3)drlg drillingDRT Drift Reduction TechnologyDSD Diatomite Steam DriveDSDP Deep Sea Drilling ProjectDSI Dipole Shear Sonic Imager (Schlumberger)DSI-2 Dipole Sonic Imager (SCHLUMBERGER tool)DSLL Shallow Laterolog MDLDSLT Digitizing Sonic Logging (Schlumberger)DSN Dual Spaced Neutron (HALLIBURTON)DSNSO DSN StandoffDSPF Far Density Spectrum PDSDSPN Near Density Spectrum PDSDSS Data Survenance SystemDSST Dipole Shear Sonic Imager (Schlumberger)DST 1) Drill Stem Test; 2) Developmental SteamDST Dual Laterolog with SRT (Schlumberger)DSV Diving Support VesselDT sonic, compressionalDT Sonic transient time.DT1A 3-5ft Delta Time ATSDT2A 3-4ft Delta Time ATSDT3A 8-10ft Delta Time ATSDT34 3-4' Compensated Sonic MSSDT35 3-5' Compensated Sonic MSSDT1B 3-5ft Delta Time ATSDT2B 3-4ft Delta Time ATSDT3B 8-10ft Delta Time ATSDT45 4-5' Compensated Sonic MSSDT46 4-6' Compensated Sonic MSSDT56 5-6' Compensated Sonic MSSDTC1 3-5ft Compensated Sonic LCSDTC2 3-4ft Compensated Sonic LCSDTC3 8-10ft Compensated Sonic LCSDTC1 3-5ft Compensated Sonic ATSDTC2 3-4ft Compensated Sonic ATSDTC3 8-10ft Compensated Sonic ATSDTEP PTS Differential Temperature PRDDTS sonic, shearDTSM Smeared 3-4' Sonic

DUM6,7,8,9 Dummy 6 or 7 or 8 or 9DWST Digital Waterform Sonic (Schlumgerger)DWT 1) Dead weight tonnage; 2) Developmental Waterdxo Flushed zone diameter (Bore hole environment)

E

E9M3 Billion cubic metresEAG Environmental Assessment GuidelinesEAP Employee Assistance ProgramEAR Division of Earth Sciences, NSFECR East Coast RepositoryECS Elemental Capture Spectroscopy (sp)EDLS Engineering Document Logging SystemEDS Enterprise Data StoreEDST Eastern Daylight Savings TimeEGR Exhaust Gas RecirculationEHS Environmental, Health, and SafetyEI Earth ImagerEIA Energy Information Administration, DOEEII Energy Information Inc.EIS Environmental Impact Statement, a document that attempts to predict the effects of a major development might have on the human and natural environments of a given geographic area. An EIS is prepared to enable industry, government and the public to consider the environmental costs and benefitsof a development project. Based on the information contained in the EIS, decisions an be made on whether to proceed with the development project.elev elevationEMC Environmental Monitoring and ComplianceEMD Energy Mineral Division, AAPGemf electromotive force / electrical voltagesEMI Electrical Micro Imaging (HALLIBURTON)ENS Epithermal Neutron SondeEOP Emergency Operations PlanEOR Enhanced Oil RecoveryEP Entry PointEPHI water-filled porosity, measurement of very near wellbore regionEPT Electromagnetic Propagation Tool (a shallow tool. May be used to check steam flooding effect. Can be used to derive EPHI)EPT Schlumberger’s dielectric logEPA United States Environmental Protection AgencyEPCA Energy Policy and Conservation Act of 2000EPH Extractable Petroleum HydrocarbonEPHI EPT porosityEPIC engineer, procure, install and commissionEPOR CLAY CORRECTED DENSITY NEUTRON X-PLOT POROSITY (Halliburton)EPT Electromagnetic propagation toolER engineering regulationERAMS Environmental Radiation Ambient Monitoring SystemERTS Earth Resources Technology Satellite (ERTS)ES Electric SurveyESD Emergency Shut-DownESG Engineering Seismology Group, IncESP Electric Submersible Pumpest EstimatedEST Exploratory SteamEUB Energy and Utility Board of AlbertaEUR Estimated ultimate recovery

EV Expected ValueEWP4 EWR - Phase 4 (HALLIBURTON SPERRY SUN)EWR-M5 EWR-M5 Resistivity (HALLIBURTON SPERRY SUN)EWR-P4D EWR-Phase 4D Resistivity (HALLIBURTON SPERRY SUN)EWRS Electromagnetic Wave Resistivity (Shielded)EWT Exploratory Water

F

F degree Fahrenheit (C = (F-32)*5/9FBFR Fullbore Flow Rate PRDFBHP Flowing Bottomhole PressureFCAA Federal Clean Air ActFCCP Caliper RawFCD Future casing (outer) diameterFCIT MFC Internal Temperature MFTFCS Fluid Conductivity SondeFD Fluid densityFDC formation density compensated, also called density logs, determine porosity by measuring the density of the rocks. Because these logs overestimate the porosity of rocks that contain gas they result in "crossover" of the log curves when paired with Neutron logs.FDEN Fluid Density PRDFDLT Delta Flow PRDFDNS Fluid Density Raw PRDFDS Fluid Density SondeFDZ Fault Damage ZoneFDV Fault Detect VolumeFe IronFEFE Shallow FE MFEFEFR Shallow FE (No Correction) MFEFEED front end engineering and designFFS Full Bore Flowmeter SondeFGD fire and gas detectionFGDC Federal Geographic Data CommitteeFGDS fire and gas detection systemFH Flooded ThicknessFIAC Four Independent Arm Caliper (HALLIBURTON)FIH Fluid In HoleFIS Fuzzy Inference SystemFIT Formation Interval TesterFIV Formation Isolation ValveFL Fluid LossFLMNH Florida Museum of Natural Historyfluor fluorescencefm formationFMAG Field MagnitudeFMI Formation Micro Image logFMNH Field Museum of Natural HistoryFMS Formation MicroScanner (Schlumberger)FMT Formation Multi-TesterFo Dual Water formation factorFO Fiber OpticFP Flowing PressureFPDSO floating production, drilling, storage and offloading facilityFPCC Formation Pressure (Cylindrical) RFSFPGP Paine Pressure Raw MFTFPGT Paine Gauge Temperature MFTFPF floating production facility

FPHI PorosityFPP Fluid Participation PercentFPQC Quartzdyne Pressure (C)FPQH Quartzdyne Pressure (T)fps feet per secondFPSO floating production, storage and offloading facilityFPSS Formation Pressure (Spherical) RFSfrac fracturedFS Feasibility StudyFSAB Financial standards accounting boardFSAL Fluid salinityFSCO Formation salinity correction optionFSU floating storage unitft Foot or feetFTMD log of overall capture gamma ray count rate for far detectorFTOT Total Flow PRDFVF Formation Volume Factor, Bbl/stbFWHP Flowing Well Head PressureFWKO Free-water KnockoutFWS United States Fish and Wildlife Service, United States Department of InteriorFWS Full Wave Sonic (FWST, HALLIBURTON)FWV Flow Wing Valve (also known as Production Wing Valve on a Xmas tree)

G

g gramG&OCM Gas- and Oil-Cut Mudgal gallonGAMGASD UNCORRECTED GAS POROSITY FROM TIME DOMAIN (Halliburton)GBS gravity based structureGBT Gravity Base TankGC Gas CutGC Gas Chromatography (the separation of a mixture of compounds (solutes) into separate components, which then can be analyzed by a mass spectrometer to yield detailed empirical molecular information regarding the chemistry of the samples).GC/MS Gas Chromatography/Mass Spectrometry (highly sophisticated instrument that identifies the molecular composition and concentrations of various chemicals in water and soil samples). GCGR Corrected Gamma Ray SGSGCL Geo-synthetic Clay LinerGCM Gas-Cut MudGCODGCR Gulf Coast RepositoryGCSE Generalized caliper selectionGD Grain densityGDEV Average angular deviation of borehole from normalGeoTap GeoTap Formation Tester (HALLIBURTON SPERRY SUN)GGRD Geothermal gradientGH Gross thicknessGIIP Gas Initially In PlaceGIS Geographic Information System (a computer system designed for storing, manipulating, analyzing, and displaying data in a geographic context).GL Ground LevelGLF Geophysical Log FacilityGLL Groningen LaterologGLLV Groningen Voltage

GLM Gas Lift Mandrel (alternative name for Side Pocket Mandrel)GLC Gas Liquid Chromatography (a liquid is supported by a base of solid material for the separation of the mixture of gases).GLV - Gas Lift ValveGMC Alaska Geologic Materials CenterGMP Groundwater Monitoring Plan (groundwater monitoring plan normally involves a network of monitoring or observation wells or micro wells and indicates the procedures and necessary documentation involved). GNT Neutron log (old, no longer used)GOCO Government Owned/Contractor Operated facility is a manufacturing plant that is owned by the Government and operated under contract by a non-government, private firm. GOR Gas to oil ratioGP Geco-Prakla Inc.gpd gallons per day (Unit of measurement used for small liquid flow rate. Generally the flow rate on most showerheads is 2.5 gallons per minute or 3600 gallons per day). GPGR Geo-Pilot Azimuthal Gamma Ray (HALLIBURTON SPERRY SUN)gpm gallons per minute (Unit of measurement used for liquid flow rate. Generally the flow rate on most showerheads is 2.5 gallons per minute). Gpm/sf Gallons per minute per square footGPH Gross Pay ThicknessGPQ Gravel Pack Quality Log (palsed nutron capture tool, Schlumberger)GPR Ground Penetrating Radar, a geophysical technology that uses radio waves to detect buried objects and the internal structure of landforms. Ground swell: (1) Long high swell in deep water. (2) Also, this swell as if rises to prominent height in shoal water. GPV Gross Pore Volumegr graygrn greenGR Gamma Ray logGr° Standard Gibbs free energy, the energy associated with a chemical reaction at standard state conditions \that can be used to do work. The free energy of a system is the sum of its enthalpy plus the product of the temperature and the entropy of the system.GRBG Gamma Ray (API) MBNGRCF PSD Gamma Ray RawGRCL DLS Gamma Ray Raw DLSGRD4 PSD Gamma RayGRDI Gamma Ray AISGRGC Gamma Ray MCGGRLL DLS Gamma RayGRMAX HILT gamma ray maxGRMIN HILT gamma ray minGRNGRO Gasoline Range OrganicsGRPO Potassium Gamma SGSGRPSiV Gravel Pack Evaluation SiActivation (palsed nutron capture tool, Schlumberger)GRPSiFe Gravel Pack Evaluation using Si-Fe (palsed nutron capture tool, Schlumberger)GRSE Generalized mud resistivity selectionGRSG Spectral Gamma Ray SGSGRSO Gamma Ray StandoffGRST Spectral Gamma Ray Logs (Schlumberger)GRTH Thorium Gamma SGSGRUR Uranium Gamma SGSGRV Gross Rock Volume

GSA General Services Administration, an agency whose purpose is to "help federal agencies better serve the public by offering, at best value, superior workplaces, expert solutions, acquisition services and management policies." The GSA organization consists of the Federal Supply Service, the Federal Technology Service, the Public Buildings Service, the Office of Government wide Policy, and various Staff Offices, including the Office of Small Business Utilization, the Office of Citizen Services and Communications, and the Office of Civil Rights.GSA Geological Society of AmericaGSP Generalized smear potentialGST Gamma Ray Spectrometry ToolGTL Gas To LiquidGTS Geostatistical Temporal-Spatial Algorithm A long term monitoring network optimization technique that uses a geostatistical method known as "kriging" to optimize sampling frequency and define the network of essential sampling locations.GTSE Generalized temperature selectionGV Gross Volume, GV = GH * AreaGVF Gas-formation Volume FactorGW Groundwater, the supply of fresh water found beneath the Earth's surface in the interstices between soil grains, in fractures, or in porous formations. Because groundwater is a major source of drinking water, there is growing concern over contamination from leaching agricultural or industrial pollutants or leaking underground storage tanks. GWM Groundwater Monitoring, the process of measuring the physical and/or chemical properties of groundwater on a periodic basis. Concentrations of contaminants are frequently monitored to determine if they are increasing, decreasing, or remaining in the same range. Monitoring is also performed at and in the vicinity of water supply sources to determine the quality and trends of indicators of water quality.GWPS Groundwater Protection Standard means the concentration of a specified constituent, statistically calculated, which is achievable with a 95% (percent) confidence level, or greater. GWTP Groundwater Treatment Plant, a facility wherein a treatment process removes suspended solids from the groundwater, destroys the contaminants in the groundwater, and prevents airborne emissions of contaminants from entering the atmosphere. Prior to discharge from the GWTP, treated water is monitored to ensure that it meets discharge limits.GYP gypsum

H

h hourHALS High-Resolution Azimuthal Laterolog Sonde (Schlumberger)HAP Hazardous Air PollutantHAZID Hazard IdentificationHCAL CaliperHDEN Vectar Processed Density MPDHDEN High Resolution Density CDSHDIL_BA High-Definition Induction LogHDIL_HAL Hostile Dual Induction (HALLIBURTON)HDIP Hexagonol DiplogHDLL High-Definition Lateral LogHDPE High-Density PolyethyleneHDRA HRDD density correctionHDRS Deep induction (Halliburton)HDSAD HILT neutron salt detection

HDTD Hostile Downhole Tension (HALLIBURTON)HEC Hydrologic Engineering CenterHFDT High Frequency Dielectric (HALLIBURTON)HGNS Highly Integrated Gamma Ray for PEX (Schlumberger)HGNS Highly Integrated Neutron Sonde (Schlumberger)HGOR High Gas-Oil RatioHGRC Herold Geological Research Centers (Denver, Houston, Abilene, Casper)HI Hydrogen indexHILTB-DTB high-resolution integrated logging tool - CTShmc Mud cake thicknessHMRC Medium induction (Halliburton)HOCM Heavily Oil-Cut Mud (drilling)HOLEV Integrated hole/cement volumeHP high pressurehp horsepowerMPERM10 MRIL PERMIABILITY (Halliburton)HPVH or HPV Hydrocarbon Pore Volume Height (I-Sw) * (Net Feet Pay) * (Porosity)HPHIECUT HILT effective porosity cutoffHRI High Resolution Induction (includes HRAI, HALLIBURTON)HRLA High Resolution Laterolog Array Tool HS&E Health, Safety and EnvironmentHSBA Releative Bearing (HS) MBNHSCO Hole size correction optionHSE Health, Safety and Environment or Health & Safety Executive (United Kingdom)HSIS HILT shale indicator selectionHSN Hostile Short Normal (HALLIBURTON)HSWCUT HILT water saturation from HITH cutoffHTDN Short Spaced Density EHT CDSHTEM HTC cartridge temperatureHUD Heads Up Digitized (from scanned, georeferenced mylar map) HVAC Heating, ventilation and air conditioningHVOL Hole VolumeHYPR Hydraulic Pressure RFSHz hertz

I

I iodideI-ES Induction SurveyIADC International Association of Drilling ContractorsIAEA International Atomic Energy AgencyIAEG International Association of Engineering GeologyIAGA International Association of Geomagnetism and AeronomyIAGLR International Association for Great Lakes ResearchIAH International Association of HydrogeologistsIAHS International Association of Hydrological SciencesIAI Inter-American Institute for Global Change Research (HQ located in Sao José dos Campos, S .(o Paulo, Brazilم

http://www.nsf.gov/stratare/egch/iaidescr.htmIAR Initial Abatement ReportIAS International Association of SedimentologistsIC Industry CanadaICAL Imaging CaliperICC Interstate Commerce CommissionICCP International Committee for Coal and Organic PetrologyICDP International Continental Drilling ProgramICES International Council for the Exploration of the SeasICL Inter-Union Commission on the Lithosphere

ICOG International Conference on GeochronologyICoTA Intervention and Coiled Tubing AssociationICRSDT International Committee on Remote Sensing and Data TransmissionICS International Commission on Stratigraphy. http://www.stratigraphy.orgICWG Ice Core Working GroupID internal diameter/Inside DiameterID Inner Diameter (of a tubular component such as a casing)ID Induction device/Induction DeepIDER Enhanced Resolution Deep PhasorIDNDR International Decade for Natural Disaster Reduction (UN declaration in 1989 established the 1990s as this)IDPH Deep-reading induction device on a Phasor Induction SFL tool

IEE Institute for Environmental Education (US)IEL Induction ElectrologIES Induction-Electrical SurveyIFS In Line Flowmeter Sondeig igneousIGBP International Geosphere-Biosphere Program: A Study of Global Change (ICSU). http://www.igbp.kva.se/IGCR International Geological Correlation Programme (UNESCO / IUGS). http://www.unesco.org/science/earth/igcp.shtmlIGY International Geophysical Year, 1957-1958 or 1955-1956 depending on source consultedIHIC International Hydrocarbon Intercomparison CommitteeIHS Information Handling Service Energy Group (formerly Petroleum Information [PI], Dwights and Petroconsultants)IHTD Differential Temperature in Deg C/sample BHTIHTF Borehole Temperature in Deg C BHTILD Induction log deep rangeILM Induction log medium rangeIMD Medium Induction LogIM Induction MediumIMER Ehhanced Resolution Medium PhasorIMLS Institute for Museum and Library ServicesIMPH Midium-reading induction device on a Phasor Induction SFL toolin InchIND InductionINQUA International Union for Quaternary Research. See http://www.inqua.tcd.ie/IODP Integrated Ocean Drilling ProgramIOGCC Interstate Oil and Gas Compact CommissionIOGS Independent Oil and Gas Service (Kansas)IP 1) Initial Potential; 2) Initial Production (drilling)IPAA Independent Petroleum Association of AmericaIPC Installed Production CapacityIPICS International Partnerships in Ice Core Sciences, activity under PAGES. See http://www.pages-igbp.org/science/initiatives/ipics/index.htmlIR Individual RiskIRIS Incorporated Research Institutes for SeismologyIRR Internal Rate of ReturnISA Instrument Society of AmericaISF Induction SFLISIP Instantaneous Shut-in PressureISCR Initial Site Characterization Report

ISPG Institute of Sedimentary and Petroleum Geology (an office of the GSC, located in Calgary, Alberta, Canada, renamed in April 1995 GSC Calgary)LSS Long-Spaced SonicISSB Isolation Sub - Spontaneous PotentialIUGG International Union of Geodesy and GeophysicsIUGS International Union of Geological Sciences. See http://www.iugs.org/IVSS Insert Vibration Severity Sensor (Halliburton)IWRC Independent Wire-rope CenterIWT Individual Well Testing?

J

J jouleJLL Jackson Log LibraryJMP Joint Mission PlanningJOI Joint Oceanographic Institutions, Inc.JOIDES Joint Oceanographic Institutions for Deep Earth Sampling

K

K potassiumK degree KelvinKB Kelly Bushingkg kilogramKGS Kansas Geological Survey

Kvaerner-SNC Lavalin Offshorekm kilometerKO Kicked OffKOP Kicked Off PointkPa kiloPascalKSLO Kvaerner-SNC Lavalin OffshorekV kilovoltKv/Kh Vertical to horizontal permeability ratiokW kilowattsKwh Kilowatt Hour

L

L 1) Liter or liters; 2) Left sideL Petroleum liquids; includes crude oil, condensate, and natural gas liquidsL/mg-m Liter/milligram - meterLACM Los Angeles County Museum of Natural HistoryLACT Lease Automatic Custody TransferLAS Logged After SurveyLAT Lateral Log, an obsolete log with a deep depth of investigationLAT Logged After Triplb Pound or poundsLC Lost CirculationLCS Long Spaced Compensated Sonic SondeLD Leak DetectionLDEN Long Linear DensityLDGP Large Diameter Gravel less PipeLDPE Low-Density PolyethyleneLDR Land Disposal RestrictionsLEDT Data Edit Curve MDLLGAS Lower Gas Detector UGD

LGR Liquids to gas ratioLIR lithology indicating ratioLL3 Laterolog 3 (HALLIBURTON)LL8LLD Line Leak DetectorLLD Laterolog deep measurementLLS Laterolog shallow measurementlm limeLMV Lower Master Valve (on a Xmas tree)LN Long Normal, an obsolete log with a deep depth of investigationLNAPL Light Non-aqueous Phase LiquidLNG Liquified natural gasLNGC Liquefied Natural-Gas Carrierloc locationLOGS Light Oil Gathering SystemLOLER Lifting Operations and Lifting Equipment RegulationsLOTS Light Oil Test StationLP low pressureLPG Liquefied Petroleum GasLPP Low Pressure Pipels limestonelse leaseLSPD Logging Speed PRDLSS Long Spaced Sonic (HALLIBURTON)LSS Low-Stand System (sedimentology)LT&C (casing)LUST Leaking Underground Storage TankLWD logging while drilling

M

m a) metre or b) earthquake magnitudeM111 Micro-Normal Conductivity MMRM222 Micro-Inverse Conductivity MMLM333 Shallow Laterolog Conductivity MDLM444 Deep Laterolog Conductivity MDLM555 Groningen Laterolog Cond. MDLM666 Micro-Res (S) Conductivity MMRM777 Micro-Res (G) Conductivity MMRM888 MMR Micro-Log Normal Cond. MMRM999 MMR Micro-Log Inverse Cond. MMRMa Million years agomA milliampereMAC Multipole Array Acoustilog BAKER ATLAS WIRELINEMAC2 Multipole Array Acoustilog BAKER ATLAS WIRELINEMACT Multi-Arm Caliper Tool (HALLIBURTON)MAGF Field Magnitude MBNMAGX X MagnetometerMAGY Y MagnetometerMAGZ Z MagnetometerMAI Compact Array InductionMATR Rock matrix typeMATR Neutron matrixMB Thousand barrelsmbd thousand barrels per dayMBD Multi Button DipmeterMBL Thousand barrels of petroleum liquids; includes crude oil, condensate, and natural gas liquidsMBN Compact Borehole Navigation SondeMBNGL Thousand barrels of natural gas liquids

MBO Thousand barrels of crude oilmbod thousand barrels of oil per dayMBOE Thousand barrels of oil equivalentmBRT metres below rotary tableMCBW Clay porosity from MRIL CTP (Halliburton)MCCO Mud cake correction optionMCF,Mcf Thousand cubic feetMCFG Thousand cubic feet of natural gasMCG Compact Comms Gamma SondeMCOR Mud correctionmd, mD Millidarcy or millidarciesMD Measured DepthMD Matrix densityMDEN Matrix densityMDN Compact Dual Neutron SondeMDL Compact Dual Laterolog SondeMDT Modular Formation Dynamics Tester, a wireline tool normally run as part of a logging program (the tool can be used to collect pressure, temperature and fluid information from most porous intervals).MDT-LFA MDT Live Fluid AnalyzerMDT Modular formation Dynamic TesterMEL Midland Energy LibraryMEM mechanical earth modelMER Maximum Efficiency RateMF MicrofiltrationMF Membrane FilterMFC Multi-Finger Caliper BAKER ATLAS WIRELINEMFCBD Thousand Cubic Feet Per DayMFE Compact Shallow Focussed ResistivityMFPSV Multifunctional Platform Support VesselMFT Compact Repeat Formation Pressure TesterMg magnesiummg molligrammg/L milligrams per literMGD Million Gallons per DayMGD Compact UltraSonic Gas DetectorMGF2 Medium 20 kHz gain factorMGG Marine Geology and Geophysics DivisionMGS Compact Gamma Submho/m mhos per meterMHT Compact High Resolution Temperaturemi MileMICLOG Microlog (HALLIBURTON)MICT Moving In Cable ToolsMID Metrix identification (plot)MIP MapInfo PlotMIR Moving In Rigmin Minute or minutesMINV Micro-InverseMIVV Micro-Inverse VoltageML Minilogml milliliterMLL Micro LaterologMLLI Micro-Laterolog CurrentMLLV Micro-Laterolog VoltageMLS Micro Log SondeMLTC MML Caliper MML/MMRMM Millionmm millimeterMMB or MMbbl Million barrels

MMBcf million cubic feet of natural gasmmbd million barrels per dayMMBL or MMbbl Million barrels of petroleum liquids; includes crude oil, condensate, and natural gas liquidsMMBNGL Million barrels of natural gas liquidsMMBO Million barrels of crude oilmmbod million barrels of oil per dayMMBOE Million barrels of oil equivalentMMBtu Million British thermal units (a heating equivalent measure for natural gas and is an alternate measure of natural gas reserves, as opposed to Mcf, which is strictly a measure of natural gas volumes. Typically, prices quoted for natural gas are designated as price per MMBtu, the same basis on which natural gas is contracted for sale).MMCF,MMcf Million Cubic FeetMMcfe million cubic feet of gas equivalent Determined using the ratio of 6 Mcf of natural gas to 1 Bbl of crude oil, condensate or natural gas liquids.MMCFG Million cubic feet of natural gasMMscf Million standard cubic feetMML Compact Micro Log SondeMMrb Millions of reservoir barrels under subsurface conditionsMMR Compact MicroLaterolog SondeMMS Minerals Management Servicemmscfd million standard cubic feet per dayMMstb Millions of stock tank barrels under standard conditionsMn ManganeseMNLI Micro-Normal CurrentMNLV Micro-Normal VoltageMNRL Micro-Normal 2"/Micro-Normal MML/MMRMO Moving Out (drilling)MODU mobile offshore drilling unitsMOF multi-objective function mol molecular weight (mole)MOR Monthly Operation ReportMPa megapascalMPD Compact PhotoDensity Sondemph miles per hourMPH2 Medium 20 kHz phase shiftMPR Multiple Propogation Resistivity (BAKER INTEQ)MRES Medium resistivityMREX Magnetic Resonance Explorer Imaging LogMRF Material Recovery FacilityMRE2 Medium real 20 kHz sonde error correctionMRIL Magnetic Resonance Imaging Log (HALLIBURTON)MRS Micro Resistivity Sondems minisecondMS1I Medium Laterolog CurrentMSIG Total porosity from MRIL CTP (Halliburton)MS1V Medium Laterolog VoltageMS2I Micro-Spherical Current 2Mscf/D Thousand Standard Cubic Feet Per DayMSDS Material Safety Data SheetMSF1 Medium LaterologMSF2 Micro-Spherically Focussed 2MSFL Micro-Spherically Focused Log (HALLIBURTON)MSFL Micro Cylindrically Focused Log for PEX (Schlumberger)MSIMSL Mean Sea LevelMSL Micro Spherical LaterologMSR2 Medium sigma reference (20 kHz)

mSS metres subseaMSS Compact Sonic SondeMST Mud sample temperatureMSW Municipal Solid WasteMTC Compact Two Arm Caliper SondeMTG Manual Tank GaugingMTK Magnetic Resonance (BAKER INTEQ)MTP Maximum Total Trihalomethane PotentialMTXD Matrix DensityMUDWT Borehole fluid weightMW megawattMW Mud WeightMWCO Mud weight correction optionMWD measurement while drillingMXE2 Medium quad 20 kHz sonde error correctionm.y. Million years

N

N/G Net gross ratioNa sodiumNACE National Association of Corrosion EngineersNAD North American DatumNASA Non Active Side Arm (term used in the North Sea for kill wing valve on a Xmas tree)NB New BitNCFBT Net Cash Flow Before TaxNCL Neutron Lifetime LogNCRF Long Spaced Neutron CNSNCRN Short Spaced Neutron CNSNCS Nuclear Combination Sonde. NCS = CDS + CNSNDAA depth differenceNDPT speed corrected depthNEB National Energy BoardNEHRP National Earthquake Hazards Reduction ProgramNEU or NEUT Neutron logNGL Natural gas liquids,liquid hydrocarbons produced with natural gas that separate from the gas as a result of decreases in temperature and pressureNGP Natural Gamma Probe (Halliburton)NGRT Gamma Ray Tool (HALLIBURTON)NGS National Geodetic Survey (NGS)NGS Natural Gamma Ray SpectrometryNGT Spectral GammaNGWA National Ground Water AssociationNIMBY Not in My BackyardNIST National Institute of Standards and TechnologyNLITH Neutron LithologyNLT Noncommercial Low TemperatureNMHC Non-Methane HydrocarbonNMOG Non-Methane Organic GasNMR Nuclear Magnetic Resonance, measures the magnetic response of fluids present in the pore spaces of the reservoir rocks. In so doing, these logs measure both porosity and permeability, as well as the types of fluids present in the pore spaces (Schlumberger).No. NumberNOAA The National Oceanic and Atmospheric AdministrationNORM Naturally Occurring Radioactive MaterialsNPH Net Pay ThicknessNPHI Neutron Porosity logNPHIS

NPO Neutron porosityNPOR Base Neutron PorosityNPOR Limestone Neutron PorosityNPRD Dolomite Neutron PorosityNPRD Dolomite Neutron PorosityNPRL Limestone Neutron PorosityNPRL Limestone Neutron PorosityNPRS Sandstone Neutron PorosityNPRS Sandstone Neutron PorosityNPV Net Present ValueNR Not RequiredNR No Returns (Drilling)NRAT Neutron Ratio (Near/Far) MDNNRAT Neutron Ratio CNSNRC US Nuclear Regulatory CommissionNRCS Natural Resources Conservation ServiceNRTF Natural Resources Trust FundNRV Non Return Valve (Chicksan valve that only allows flow in one direction)NS No ShowNSPD Derived SpeedNSR New Source ReviewNTFZ Newfoundland Transform Fault ZoneNTMD overall capture gamma ray count rate for near detectorNUCP Smoothed Neutron Porosity (Halliburton)

O

O111 Micro-Normal 2" Conductivity MRSO222 Micro-Inverse Conductivity MRSO333 Shallow Laterolog Conductivity DLSO444 Deep Laterolog Conductivity DLSO555 Groningen laterolog cond. DLSO666 Micro-Normal 2" Conductivity MRSO777 Micro-Inverse Conductivity MRSO888 Micro-Laterolog Conductivity MRSO999 Medium Laterolog Conductivity MRSO&G Oil & GasO&GCM Oil- & Gas-Cut MudO&M Operation and MaintenanceO&SW Oil & Salt WaterOBMR Oil Based Mud Imager (Schlumberger)OBS Observation OBVR Oil-to-bulk Volume RatioOC Oil CutOCM Oil-Cut MudOCS Outer Continental ShelfOD Outer Diameter (of a tubular component such as a casing)OEC Overpressure Exceedence CurveOF Open FlowOGIFF Oil and gas integrated field fileOGIP Original Gas In PlaceOH Open HoleOHSA Occupational Health and Safety ActOGIP Original Gas In Place (the total quantity of trapped gas believed to exist in a geologic feature or structure, based on the analysis of well information, geological, geophysical and petrophysical data)OI Oxygen IndexOILD UNCORRECTED OIL POROSITY FROM TIME DOMAIN (Halliburton)OIM Offshore Installation Manager

OLS Offshore Loading SystemOMRI Oil Mud Reservoir Imaging Tool HALLIBURTONOOE Offshore Operation Engineer (senior technical authority on an offshore oil platform)OOIP Original Oil In PlaceOol OoliticOpal-A amorphous opal phase ((SiO2*nH2O), a SiO2 phase exists under lower pressure and temperatureOpal-CT Cristobalite opal phase, a microcrystalline form of SiO2 converted from opal-A at moderate heat and pressure.OPEC Organization of Petroleum Exporting CountriesOpex Operating expenditureORD Compensated Bulk Density (LithoTrak)ORED Offshore Reliability DatabaseOPR OperatorOSHA Occupational Safety and Health AdministrationOSM Office of Surface Mining Reclamation and EnforcementOSP Office of Strategic PlanningOSR Oil Steam Ratio (barrels oil/barrels steam)OSWER Office of Solid Waste and Emergency ResponseOTL Operations Team LeaderOUST Office of Underground Storage TanksOVF Oil-formation Volume Factoroz ounce

P

P poiseP50 50 percent probabilityP&A Plugged and AbandonedP&S Plugged and SuspendedPa PascalPADPAU Pre-Assembled UnitP.E. Professional EngineerP.G. Professional GeologistP2 Pollution PreventionP2EA Pollution Prevention and Environmental AwarenessPA Preliminary AssessmentPADV Pad VoltagePAH Polycyclic Aromatic HydrocarbonsPAI Performance Audit InspectionPB Plugged BackPBBP Probable hehind pipePBBs Polybrominated BiphenylsPBPD Probable producingPBR Polished Bore Receptacle (component of a completion string)PBSI Probable shut-inPBTD Plug Back Total DepthPBU Pressure Build Up (applies to integrity testing on valves)PBUD Probable undevelopedPCB Polychlorinated BiphenylsPCG Pressure Case GammaPCL Pipe Conveyed LoggingPCNSS Nutron porosity (SS, Halliburton)RCP Risk Control ProcessPDFS Far Density Spectrum MPDPDK PDK-100PDI Paraffin-deposition intervalPDNP Proved shut-in or proved behind pipePDNS Near Density Spectrum MPDPDP Proved producingPDS Photo Density Sonde

PDSS Density porosity (SS, Haliburton)PE Petroleum EngineerPE Photo electric curvePe photoelectric cross section indexPEF photoelectric factorPEF Lithodensity logPEFZ Std. res. formation PEPEI Petroleum Equipment InstitutePERF Perforations/perforatedperm permeabilityPFD Process Flow DiagramsPFF Percolation Formation Factorpgas POROSITY GAS PGC Pressure Gauge CarrierPGOR Produced Gas Oil RatiopH Negative log of the hydrogen ion activityPHI Total porosityPhia Average Porosity Phia = ?(Phi*h)/?(h)Phie Effective PorosityPHIE MRIL POROSITY FROM TIME DOMAIN (Halliburton)PHIG POROSITY GAS (Halliburton)PHIMAX HILT max porosityPHIMD MRIL POROSITY FROM LONG Tw (Halliburton)PHIO POROSITY OIL (Halliburton)PHIW POROSITY WATER (UNDER POLARIZED, Halliburton)PHS US Public Health ServicePI Productivity IndexPIP Petroleum Incentive Programpk pinkPKR PackerPL PipelinePLL Probable Loss of LifePLSF Far Pulse Height TDSPLSN Near Pulse Height TDSPLT Production Logging ToolPLT/MLT Production Logging Tests/Multi-layer TestsPM Particulate MatterPMAA Petroleum Marketers Association of AmericaPMAX Phi maxPMRI MRIL PERMEABILITY USING DENSITY NEUTRON (Halliburton)PNC Palsed Nutron CapturePHHI PULSED NEUTRON HOLDUP IMAGERPNL Nuclear porosityPNS Photo Nuclear Sonde. PNS = PDS + CNSPOB Persons On BoardPOC Pump Off ControllerPOIS Poisson's RatioPOOH Pull Out Of HolePOP Putting On Pumppor porosity/porousPOSS Possible (producing, shut-in, behind pipe, or undeveloped)PP Pump Pressureppb parts per billionppe personal protective equipmentPPFG Pore Pressure/Fracture Gradientppm parts per millionppg Pounds Per GallonPR Poor ReturnsPRF Probabilistic Recovery FactoryPROB Probable (producing, shut-in, behind pipe, or undeveloped)PROP 1) propagation time (TPL or TPW); 2) Proposed

PROX Proximity LogPSBP Possible behind pipePSD Precision Strata Dipmeterpsi pounds per square inchpsia Pounds Per Square Inch AbsolutePsig Pounds per square inch gougePsi/ft Pounds per square inch per footPSM Process Safety ManagementPSPD Possible producingPSSI Possible shut-inPSUD Possible undevelopedPTCO Pressure temperature correction optionPTO Power TakeoffPTS Pressure Temperature SondePUD Proved UndevelopedPUR Plant Upset ReportPUWER Provision and Use of Work Equipment RegulationsPV Plastic ViscosityPVBP Proved behind pipePVC Polyvinyl ChloridePVCapex Present Value Capital expenditurePVH Pore Volume HeightPVPD Proved producingPVPI Present Value Profitability IndexPVSI Proved shut-inPVT Pressure, Volume, Temperature (reservoir engineering)PVT Pit Volume Totalizer (drilling)PVUD Proved undevelopedPWD Pressure While Drilling HALLIBURTON SPERRY SUN tool codePWS Public Water SystemPWV Production Wing Valve (also known as a flow wing valve on a Xmas tree)

Q

QA Quality AssuranceQA/QC Quality Assurance/Quality ControlQPG Quartz Pressure GaugeQRA Quantitative Risk Assessmentqtz quartzqtze quartzite

R

R 1) degree Rankine; 2) Right side; 3) RedR&M Well Repair and MaintenanceR&R Well Reconditioning and RecompletionRAI Relative acoustic impedance (seismic)RAKT Thorium/Potassium Ratio SGSRAKU Uranium/Potassium Ratio SGSRATS Radioactive Tracer Survey RAUT Thorium/Uranium Ratio SGSRAZI Azimuth of Reference MBNrb Reservoir barrelRBAD Relative Bearingrcf reservoir cubic feetRCI Reservoir Characterization InstrumentRCOR Rotary Sidewall Coring ToolRCP Risk Control ProcessRCRA Resource Conservation and Recovery Act

RDLI (Atlas)RDT Reservoir Description Tool (HALLIBURTON)RDW Reporting Data WarehouseRE Reservoir Engineerrec recovereREST logRFG Reformulated GasolineRFLI (Atlas)RFS Repeat Formation SamplerRFT Repeat Formation Tester (a high resolution down hole logging tool which records reservoir pressures at multiple points in a well and may on occasion be configured to obtain several small samples of gas, oil and/or other fluids over a reservoir interval).RH Reservoir ThicknessSh Hydrocarbon saturationRHGF (G/C3)RHOB Density logRHOFLU Fluid densityRHOMAT Matrix densityRHOZ Formation densityRIH Run In HoleRILD Deep Induction ResistivityRILM Medium Induction ResistivityRIN log of inelastic gamma ray count rate ratio between detectorsRKB Rotary Kelly Bushing (a datum for measuring depth in an oil well)RLA Recovery Land Acquisition Grants ProgramRm Mud resistivityRmc Mud cake resistivityRmf Mud filtrate resistivity (Bore hole environment)Rmfe mud filtration equivalent resistivitrmg reamingRMS Mud Resistivity SondeRMSF Rm Resistivity RMSrng runningRo Uninvaded zone resistivity 100% Sw. Bore hole environmentRo Vitrinite reflectance, in oilROD Rich-Oil DemethanizerROG Reactive Organic GasROP Rate Of PenetrationROR Rate Of ReturnROV Remotely Operated VehicleRP Reduced PressureRP Rock PressureRPM Reservoir Performance MonitorRPM Rotoary Rev/MinRPV Reservoir Pore VolumeRRB Rerun BitRRV Reservoir Rock VolumeRs Shoulder or adjacent bed resistivityRSCT Rotary Sidewall Coring (HRSCT, HALLIBURTON)RSDF Far Resolution Curve PDSRSDN Near Resolution Curve PDSR SFE Shallow Focussed ElectricRSFR Shallow Focussed Electric RawRSHL ?shaleRSS rotary steerable systemRSSC Received SignalRSSN Received Signal RawRST Reservoir Simulation Tool

Rt True electrical resistivity of a formation (uninvaded zone, this symbol is used in petrophysical calculations to represent the true electrical resistivity of a formation).RT Rotary TableRTBF log of the ratio of capture count rates from the borehole relative to capture count rates from the formationRTLC Rt Conductivity MDLRTMD Log of capture gamma ray count rate ratio between detectorsRTP Return To ProductionRTS Radioactive Tracer Survey RUCT Rigging Up Cable ToolsRUR Rigging up rotary rig.RVP reid vapour pressureRw electrical resistivity of formation water (Formation water resistivity)RW Resistivity of connate water/formation water resistivityRwe Water equivalent resistivityRxo Flushed zone resistivity.RXOC Rxo Conductivity MDLRXOZ Micro-resistivity log (Schlumberger)RXOL Rxo MDLRXRT Rxo/Rt AISRXRT Rxo/RtRz Fluid resistivity of transition zone

S

s, sec SecondsS/T Sample ToolsS175 Solar 175SAII SlimXtreme Array Imager (Schlumberger)SAAII SlimAccess Array Induction Image Tool (Schlumberger)SAG Seismic Air GunSAGD Steam Assisted Gravity Drainage (SAGD)SAL1 Fluid Conductivity PRDSAR a) Search and Rescue; b) synthetic aperture radarsat saturated, saturationSBL Sea bed logging (used to to detect and characterize hydrocarbon bearing reservoirsin deep water areas)SBL SP curves with baseline shifted SBM a) synthetic-based mud or b) Single Buoy MooringSBR Shoulder bed resistivity factorSBT Segmented Bond Toolscf standard cubic feetscf/d Standard Cubic Feet / DaySCG Sidewall Core GunSCSSV Surface Controlled Sub-surface Safety ValveSD Steam Drivesd, ss sand, sandSDC Scratcher Dipmeter SondeSDEN Short Linear Density CDSSDL Significant Discovery LicenceSDL Spectral Density Log (HALLIBURTON)SDO Shut Down for OrdersSDTK Accoustic Porosity Explorer (BAKER INTEQ)SDWA Safe Drinking Water ActSDWARS Safe Drinking Water Accession and Review Systemsdy SandySec sectionSED Six Arm Dipmeter (HALLIBURTON)

SED SedimentSEG Society of Exploration Geophysicistsseis seismographSEIS Socio-Economic Impact StatementSEM scanning electron microscopeSEPM Society for Sedimentary GeologySEPTAR Shell Exploration and Production Technology and Research (SEPTAR)SEPTCo Shell Exploration & Production Technology CompanySFA Slowness Frenquency AnalysisSFCR SFL channel ratioSFD Simultaneous Formation Density (Halliburton)SFEI Focussed Electric CurrentSFL Spherically Focused Log, a frequently used log with a shallow depth of investigationSFLA AFL AverageSFLE SFL enableSFOC Shallow focus logSFOGI Shell Frontier Oil & Gas Inc.SFT Sequential Formation Tester (HALLIBURTON)SG Samuel GeologicalSG Survey GasSG Show of GasSGBN log of cross section (sigma) for borehole (near detector);SGDT Spectral Gamma SpectrumSGSSGFM log of cross section (sigma) for formation (far and/or near detector); SGPF Strain Gauge Pressure RFSSGR Shallow Guard Log (A frequently used log with a shallow depth of investigation)SGR Spectral Gamma Ray (HALLIBURTON)SGR Shale Gouge RatioSGS Spectral Gamma Sondesh shaleSHEAR open hole shear wave velocity log SHT Surface hole temperatureSI Shut InSIBHP Shut-In Bottom Hole PressureSICP Shut in casubg pressureSIDPP Shut-In Drill-pipe pressureSIEP Shell International Exploration and ProductionSIP shut In PressureSITHP Shut In Tubing Hanger Pressure (another term for CITHP)SJV San Joaquin Valley, CaliforniaSJVAPCD San Joaquin Valley Air Pollution Control District

CaliforniaSL SpectralogSLD Stabilized Litho Density (Halliburton)SLL Shallow LaterologSLLI Shallow Laterolog CurrentSLLV Shallow Laterolog VoltsSN Short Normal (An obsolete log with a shallow depth of investigation)SNG Synthetic or Substitute Natural GasSo Oil saturation (Percentage of oil in pore space)SO&G Show of Oil and GasSO&W Show of Oil & WaterSoa Average oil saturation, Soa = ?(So * Phi * h) / ?(Phi * h), where h-thickness, Phi-total porositySOCN Standoff distanceSOCO Standoff correction option

SOE System of Operating ExcellenceSOEP Sable Offshore Energy ProjectSOP Standard Operating ProcedureSoPhi Bulk Oil Saturation, the product of oil saturation (Sa) and porosity (Phi)SoPhiH Bulk Oil Column HeightSOW Scope of WorkSP Spontaneous Potential log, also called Self PotentialSPCC Spill Prevention, Control, and CountermeasuresSPCG Spontaneous PotentialSPCLEAN HILT SP cleanspd spuddedSPDL SP MDLSPDR SP driftSPHI SONIC POROSITY (DTM=55 5)SPLL DLS Spontaneous PotentialSPM Single Point MooringSPM Side Pocket MandrelSPM Stroke/Min.SPNV SP next valueSPO Sonic PorositySPODDS Stanford Deep Water Geosciences GroupSPOR Sonic Porosity ATSSPR Raw Spontaneous PotentialSPRD Dolomite Sonic Porosity MSSSPRL Limestone Sonic Porosity MSSSPRL Laterolog SPSPRL Laterolog SP DLSSPRS Sandstone Sonic Porosity MSSSPsdSPSHALE HILT SP shaleSPWLA Society of Petrophysicists & Well Log Analystssq Squaresqu squeezeSr strontiumSRES shallow resistivitySRFT Slim Access Repeat Formation Tester (Schlumberger)SRS Seismic Reference SondeSS, ss subseaSSA Sole Source AquiferSSF Shale Smear FactorSSLT SlimAccess Sonic Logging Tool (Schlumberger)SSO Slight Show of OilSSP Static SPSSSV Sub-Surface Safety ValveSSTT Sub-Sea Test TreeSSU Saybolt seconds universalSTAR Simultaneous Acoustic and Resistivity ImagerSTATEMAP State Geological Mapping Programstb Stock-tank barrelSTB/D Stock-tank Barrels per DaySTC Slowness-Time-Coherencestd Standardstds standsSTGS South Texas Geological Society STK Resistivity Imaging (StarTrakstn stainSTOIIP Stock Tank Oil Initially In PlaceSTOOP Stock Tank Original Oil in PlaceSTOP Safety Training Observation Programstrks streaks

sul wtr sulphur watersur surveySUVA Specific Ultraviolet AbsorbanceSVD Singular Value Decomposition (seismic)SVSS Sonde Vibration Severty SensorSW Salt WaterSw/SW Water Saturation/Uninvaded zone water saturation (Percentage of water in pore space)Swb fractional portion of total porosity saturated with clay bound waterswbd swabbedswbg swabbingSWBM SWB (Halliburton)SWC Sidewall Cores (HALLIBURTON)Swi Transition zone water saturationSWP Safe Work Plansx sacksSxo Flushed zone water saturationSXO FLUSHED ZONE GAS SATURATION (Halliburton)SYST Surface System

T

T or T/ Top oft tonne (a metric ton).T/HSS Transgrressive/High-Stand System (sedimentology)TA Temporarily AbandonedTAC Two Arm CaliperTAI Thermal Alteration IndexTBFZ Trans-Basin Fault ZoneTBRT Thin-Bed ResistivityTBTV Tension of CableTCE TrichloroethyleneTCF Trillion Cubic FeetTCFG Trillion Cubic Feet of natural GasTCP Tubing Conveyed PerforatinTCS Tension Compression SubTD Total DepthTD Total depthTDC Top Dead CenterTDD Total depth - drillerTDEP True Depth PSDTDFE Tension Of CableTDL Total depth - loggerTDS Thermal Neutron Decay SondeTDSI Tension Of CableTDT Thurmal Decay TimeTDT-P Dual-Burst Thermal Decay Time (Schlumberger)TENORM Technologically Enhanced Naturally Occurring Radioactive MaterialTENS TensionTEXD Borehole TemperatureTEXF PSD Borehole TemperatureTEXL DLS Borehole TemperatureTEXN Borehole Temperature CDSTG 1) Trip Gas; 2) Temperature GradientTGASTGOR Total Gas Oil Ratio (GOR uncorrected for gas lift gas present in the production fluid)THM Trihalomethane

THP Tubing Hanger Pressure (pressure in the production tubing as measured at Tubing-Hanger"THUMS Texaco, Humble (now Exxon), Unocal, Mobil, and Shell (consortium)TIF Test Independent FailureTILD Borehole TiltTIND Sonde TemperatureTLP Tension Leg Platform.TLS Target Levels of SafetyTMD-L Thermal Multigate Decay-Lithology (HALLIBURTON)TNPH Thurmal Nutron Porosity (may be environmentally corrected)TNTC Too Numerous To CountTO Temperature ObservationTOC 1) Total Organic Carbon; 2) Top Of Cement (casing)TOG Total Organic GasesTOT Time of TravelTP Tubing PressureTPC Tennessee Petroleum CouncilTPD Tons Per DayTPH Total Petroleum HydrocarbonsTPS Total Petroleum SystemTR Temporary RefugeTR01 AST Trace 1TR02,3,4,5,6 AST Trace 2, 3, 4, 5, 6TRSCSSV Tubing Retrievable Surface Controlled Sub-Surface ValveTRSCSSSV Tubing Retrievable Surface Controlled Sub-Surface Safety ValveTSCA Toxic Substance Control ActTSP Total Suspended ParticulateTSR Temporary Safe RefugeTSS Total Suspended Solidststg testingTSURF Surface temperatureTTHM Total TrihalomethanesTTK Formation Multi-Tester (TesTrak, BAKER INTEQ)TTRM Temperature/Tension/Mud Resistivity SubTVD True Vertical DeptTwp TownshipTWS Temperature of connate water sampleTWT Two-Way Travel timeTWWA Tennessee Water and Wastewater Association

U

UBI Ultrsonic Borehole Imager (Schlumberger)UCE Ultrasonic Pipe Integrity (Schlumberger)UCIT Ultrasonic Corrosion Imager (Schlumberger)UDR ultradeep-resistivityUF Ultrafiltrationug/L micrograms per LiterUGD Ultrasonic Gas DetectorUGAS Upper Gas Detector UGDUIC Underground Injection ControlUICW Underground Injection Control WellsUKOOA United Kingdom Offshore Operators AssociationULCC Ultralarge Crude CarrierUMV Upper Master Valve (from a Xmas tree)unconf unconformityUOIL Used OilUPMS ExxonMobil Upstream Project Management SystemUPRC ExxonMobil Upstream Research Center

USCE United States Corps of EngineersUSCFCCCHR University of Southern California, Foundation for Cross-Connection Control and Hydraulic ResearchUSCOE United States Corps of EngineersUSDA United States Department of AgricultureUSDHHS United States Department of Health and Human ServicesUSDOE United States Department of EnergyUSDOI US Department of InteriorUSDW Underground Source of Drinking WaterUSGS United States Geological SurveyUSIT Ultrasonic Imaging Tool (Schlumberger)USNRC United States Nuclear Regulatory CommissionUST Underground Storage TankUSWRC United States Water Resources CouncilUTC Unit Technical CostUTM Universal Transverse MercatorUTS Universal Treatment StandardsUV Ultraviolet Light

V

v VoltVAR Shell Value Assurance ReviewVCS vessel control systemVEC0 Shallow InductionVEC1 Near InductionVEC2 Near Medium InductionVEC3 Far Medium InductionVEC4 Far InductionVEC5 Deepest InductionVHF very high frequencyVLCC Very Large Crude CarrierVLMS Micro-Sonic Velocity CSSVLSF Velocity (S) CSSVOA Volatile Organic AnalysisVOC Volatile Organic ChemicalVOC Volatile Organic CompoundsVRP Visibility Reducing ParticlesVS Velocity Surveyvs versusVSHL v-shaleVSP Value Screen PricesVSP vertical seismic profile (walkaway VSP)VSS Vibration and Stick Slip (BAKER INTEQ)VTI Vertically Transverse IsotropicVWVX1 Vx Receiver 1VX2,3,4 Vx Receiver 2, 3, 4

W

W wattW/C Water CushionWAG Water Alternating Gas (describes an injection well which alternates between water and gas injection)WAV3 AmplitudeWAV4 Two Way Travel TimeWAV5 Compensated AmplitudesWBM A drilling mud in which the continuous phase is waterWC WildcatWEG Wireline Entry Guide

WF Water Floodingwh whiteWHM Wellhead maintenanceWHMIS Workplace Hazardous Materials Information SystemsWHP Wellhead PressureWLTS Well Log Tracking SystemWLTS Well Logging Transaction SystemWO/O Waiting On OrdersWOA Well Operations AuthorizationWOC Water Oil ContactWOC Waiting On CementWOE Well Operations Engineer (a key person of Well services)WOR water-oil ratioWPC Water Pollution ControlWQ TEXTURAL PARAMETER USED FOR CBVWE COMP (Halliburton)WQCA Water Quality Control ActWQCB Water Quality Control BoardWQP Water Quality ParametersWR Wet resistivityWRC United States Water Resources CouncilWRSCSSV Wireline Retrievable Surface Controlled Sub-Surface ValveWSCD Wave Sonic Cross Dipole (HALLIBURTON)WS Work StationWSD WaveSonic Dipole (WSST, HALLIBURTON)WSR Work Station ReadyWSS Well Services Supervisor (leader of Well services at the wellsite)wt. WeightWTF Well trajectory flagWTRD UNCORRECTED WATER OROSITY FROM TIME DOMAIN (Halliburton)WTS ECLIPS WTS Downhole Common RemoteWW Water WellWWP Water Well Program

X

XC Cross-connection, cross correclationxln crystallineXMAC Cross-Multipole Array AcoustilogXMAC-E XMAC Elite (Next generation XMAC)XMRI Extended Range Micro Imager (HALLIBURTON)XPERM Matrix Permeability in the X-directionXPHLOC Crossplot Selection for XPHIXPOR Crossplot PorosityXPT Formation Pressure Test tool (Schlumburger)XYC XY Caliper Log (HALLIBURTON)

Y

yd yardyr. year

Z

ZDENP Density logZDL Compensated Z-Densilog

ZOI Zone of Influence