Petrophysical evaluation system

DecisionXpress

Applications■ Casing, drilling-ahead, and

sidetracking decisions

■ Mechanical and percussionsidewall coring planning

■ Pressure-measurement and reservoir-fluid samplingplanning

■ Drillstem testing operations

■ Completion strategies

■ Sensitivity analysis

Benefits■ Reduced costs through better

and earlier decisions

■ Risk minimization and costoptimization for testing, sampling, and completionstrategies

■ Robust petrophysical evaluation in siliciclastics

■ Quantitative mineralogy,porosity, and water saturation

■ Identification of porous and permeable zones

■ Movable fluid determination

■ Qualitative producibility

■ Net-to-gross pay indication

■ Log data and interpretationproduct quality control

■ Realization of the full potentialof Schlumberger data acquired

Features■ Highly automated; minimum

user input required

■ Quantitative lithology fromSpectroLith* processing

■ Quality control for tool operation and measurement

■ Matrix-corrected porosity

■ Waxman-Smits water saturation equation

■ Interactive parameter selection from crossplots, histograms, and log displays

■ Reservoir properties calculated by zone

■ Log ASCII Standard (LAS) file generation

■ PDF printing capability

■ Interactive plot for selectionof sidewall core, pressure,and fluid sampling points

Fast, nearly automatic log interpretation for completion decisionsOperators require fast, objective, and reliablelog interpretation to help make completiondecisions. A nearly automatic service forprocessing data from modern spectroscopyand conventional logging tools is the answer.

There has long been a need for a petro-physical answer, comprising at least poros-ity and water saturation, in real time orwithin a few hours of logging. Attempts toprovide such a product have been hamperedby the necessity of defining numerousparameters and well zonations manually.That process required the timely availabilityof a skilled interpreter or an establisheddatabase for the reservoir or formation.

A preferable approach is to determine asmany parameters as possible automatically.With the introduction of elemental concen-tration logs and SpectroLith quantitativelithology processing, mineralogy and matrixparameters can be derived automaticallywith greater accuracy and with much lesssubjectivity than possible with conventional,time-consuming techniques using onlytriple-combo logs. The number of inputparameters required is therefore reduceddramatically, to only formation water salinity in the optimum case.

Using detailed petrophysical evaluation available only minutes after logging, key decision-makers can collaboratefrom anywhere in the world with secure Web-based access.

Get petrophysical interpretation within minutes after logging—at the wellsite or anywhere else it’s needed.The DecisionXpress service integratesdata from the Platform Express* inte-grated wireline logging tool and uniqueECS* Elemental Capture Spectroscopyservices in a powerful interpretation software program.

The stand-alone, PC-basedDecisionXpress Viewer application provides rapid data visualization andreprocessing capabilities with minimaluser inputs, and it delivers a robustpetrophysical evaluation in sand-shalereservoirs through the secure Web-based InterACT* real-time monitoringand data delivery system.

Applications include planning of coringand sampling operations; decisions forcasing, drilling ahead, or sidetracking; andthe design of completion strategies.

The basis for the DecisionXpress serviceFundamental to the new DecisionXpresssolution are the mineralogy and matrixproperties derived from ECS-measuredelemental concentrations and SpectroLithprocessing. This information removesmost of the subjectivity in conventionallog interpretation and supports accurateand consistent evaluation results.

At each depth level the processing flowslinearly, starting with the mineralogy andmatrix properties and proceeding throughthe computation of matrix-corrected poros-ity, permeability, and fluid saturations.

The entire computation is performed inminutes after data acquisition, and in mostsituations the computation requires theselection of only one parameter, forma-tion water salinity. The results provide all the log-derived inputs needed for deci-sions on completions, pressure and fluidsampling, and sidewall core sampling.

Unlike conventional products thatmust be adapted to specific environments,DecisionXpress results are accurate andreliable in most siliciclastic reservoirsaround the world.

Siderite

Porosity

Clay BoundTENS

10,000 0

Net

Pay

ECGR

0 200(gAPI)

Lithocolumn

RSKPLVolumetric

0 1(ft3/ft3)

Clay

QFM

Carbonate

Pyrite

Porosity

0.5 0(ft3/ft3)

Moved Hydrocarbon

Hydrocarbon

Free Water

Capillary Bound

KINT

10,000 0.1(mD)

Water Cut

1 0

Hydrocarbon

Water

Flow Profile

0 1

Hydrocarbon

Water

HCAL

6 16(in.)

BS

6 16(in.)

Washout

MD

1:400 ft

(lbf)

Mudcake

Quality Flag Descriptions for DecisionXpress Computations

Reliable Warning Data outside of DecisionXpress tolerance specifications.

LQC Track

L : Lithology/Mineralogy (QC_LITH)P : Porosity (QC_PORO)K : Permeability (QC_PERM)S : Saturations (QC_SW)R : Relative Permeabilities (QC_RELPERM)

This answer product, available minutes after data acquisition, provides all the log-derived inputs neededfor decisions on completions, pressure and fluid sampling, and sidewall core sampling.

A. The Pay flag is set by cutoffs on porosity, permeability, and total water saturation.

B. The Net flag is set by using cutoffs on total porosity and permeability.

C. A gray mask indicates that results are outside DecisionXpress tolerance specifications.

D. Porosity, permeability, and saturation measurements are displayed for siliciclastics only.

E. The normalized flow profile indicates the zones with highest producibility potential.

F. Water cut indicates that this hydrocarbon zone will produce without water.

G. The Porosity Quality flag is raised because the density measurement exceeds quality controltolerances in the washed-out zone.

H. The Lithocolumn is based on SpectroLith mineralogy inputs and is useful for well-to-wellcorrelation.

I. Quality flags are ordered hierarchically. If Lithology track data are flagged as questionable,all tracks are flagged.

I

C

A

E

B

D

F

H

G

PC-based viewer software delivered with the data enables interactive parameter selection from crossplots, histograms,and log displays.

A. The formation and reservoir zones canbe set interactively.

B. Changing a formation or reservoir param-eter updates the results instantly.

C. Zone parameters can be changed inter-actively by dragging this vertical line orby keying a change into the FormationZone Parameter Editor.

D. The apparent formation water salinity(FSALA) versus clay interactive cross-plot facilitates selection of the correctformation water salinity.

AB

C

D

The interactive sampling plot is very useful for selecting sampling points for sidewall cores, pressures, and reservoir fluids.

A. Clicking on new icon opens samplingplot and tables.

B. Core, pressure, or fluid sample can beselected.

C. Sample points are displayed in the threesampling tracks: sidewall core (S), pressure (P), and fluid (F).

D. Clicking on the log selects a sample. Ahorizontal hairline makes selection easy.

E. Selected points are displayed in the corresponding sampling table along with petrophysical properties at thesampling depth.

F. A sampling table summary is included in the final sampling printout.

G. Samples can be added and removedgraphically or from the tabular listing.Comments can also be included witheach sample if required.

A B

C

D

F

EG

The enabling technologies Schlumberger can provide advancedpetrophysical evaluation in near-realtime, with quality control on data inputand interpretation output, through theintegration of ECS capture gamma rayspectroscopy data and Platform Expresstriple-combo measurements. The accu-racy of ECS measurements is relativelyinsensitive to mud weight, most fluidtypes, borehole size, and rugosity.

SpectroLith quantitative lithology,which differentiates the DecisionXpressservice from other interpretation meth-ods, is based on processing the elementalrelative yields through an oxides closuremodel to produce quantitative elementalconcentration logs. This step is followedby processing through element-to-mineraland element-to-matrix property trans-forms developed from a high-quality core database.

The SpectroLith process uses meas-urements of silicon, calcium, and iron to produce as accurate an estimation of clay as is possible from a direct meas-urement of aluminum. Carbonate con-centrations are determined from thecalcium concentration log with an accu-racy that is not available from loggingdevices that do not measure elementalconcentrations. Matrix properties, includ-ing density, neutron porosity, and sigma,are also calculated from the dry-weightelemental concentrations.

The introduction of the PlatformExpress tool was a major advancementin wireline logging technology. Comparedwith a conventional triple-combo tool,the Platform Express integrated wirelinelogging tool is twice as fast, gives betteranswers, and is more cost effective torun because it requires significantly lessrig time. The system upgrades and expandstraditional resistivity and porosity meas-urements, includes high-resolution micro-resistivity measurements and imaging,and measures tool movement for real-time speed correction and automaticdepth matching with the ECS sonde.

X500

X450

X400

HydrocarbonHCAL

6 16

BS

6 16(in)

Mudcake

DEPTH .

X350

X300

X250

SWT

1 0(ft3/ft3)

SXOT

1 0(ft3/ft3)

SWI

1 0(ft3/ft3)

SWB

1 0(ft3/ft3)

RXO

0.2 2,000(ohm-m)

RT

0.2 2,000(ohm-m)

R0

0.2 2,000(ohm-m)

ASAL_WALK2

300 0.03(ppk)

FSAL

300 0.03(ppk)

FSALA

300 0.03(ppk)

PHIT

0.5 0(ft3/ft3)

DPHI

0.5 0(ft3/ft3)

CNPH

0.5 0(ft3/ft3)

RHGE

2.5 3(g/cm3)

Mineralogy

0 1(lbf/lbf)

ECGR

0 200(gAPI)

GTEM

0 300(degF)

BHPR

0 5,000(psi)

GDEV

(in)

MD

1:400 ft

CS

0 5,000(ft/h)

TENS

10,000 0(lbf)

Siderite

Depth

(ft) 5 (deg) 45

Clay

Washout

Pyrite

Carbonate

QFM Light Hydrocarbon Hydrocarbon

Clay Bound

Capillary Bound

Free Water

RSKPL

Quality Flag Descriptions for DecisionXpress Computations

Reliable Warning Data outside of DecisionXpress tolerance specifications.

LQC Track

L : Lithology/Mineralogy (QC_LITH)P : Porosity (QC_PORO)K : Permeability (QC_PERM)S : Saturations (QC_SW)R : Relative Permeabilities (QC_RELPERM)

All data interpretation is automatically and strictly quality controlled. Quality flags indicate the confidence withwhich interpretive data can be applied.

A. Total water saturation is divided into free and bound waters (capillary and clay-bound).

B. The separation between density porosity (DPHI) and compensated neutron porosity(CNPH) indicates a light hydrocarbon.

C. The formation water salinity (FSAL) used in the computation is displayed.

D. PHIT is the matrix-corrected total porosity.

E. The separation between true resistivity (RT) and water-filled resistivity (R0) indicateshydrocarbon.

F. Matrix density is computed from the ECS-measured dry weight elements and is used to correct density porosity.

G. SpectroLith processing results display the dry weight of eight minerals.

H. CNPH is fully corrected for matrix and environmental effects.

I. After matrix correction, neutron and density porosities overlay in fluid zones.

J. Apparent formation water salinity (FSALA) is computed to select the correct value in water zones.

K. The RT/R0 overlay in this water zone indicates a good choice for the formation watersalinity parameter.

A

B

C

D

E

F

G

HI J K

Make more accurate time-critical decisions.The DecisionXpress service delivers theinformation required for geoscience andengineering professionals to make lesssubjective and more accurate time-criticaldecisions through intuitive, user-friendlygraphical output displays.

PC-based viewer software deliveredwith the data enables near-real-timereprocessing wherever you choose toreceive the data. The DecisionXpressViewer application is simple enough forgeneralists and occasional users, yetadvanced enough to provide accuratepetrophysical interpretation results that can be used immediately to makeinformed decisions.

An unprecedented level of automa-tion allows unnecessary subjectivity tobe reduced significantly. Not only doesDecisionXpress software enable moreusers to get petrophysical interpretationresults, but all those users will get thesame, accurate, repeatable answer.

Realize the full potential of Schlumberger data acquired.The DecisionXpress service uses all theformation, borehole, and quality-controlmeasurements from the Platform Expressand ECS tools to produce an advancedpetrophysical evaluation with minimalrequired user inputs.

Additionally, a wide range of answerproducts is available based on the inte-gration of the SpectroLith quantitativelithology and matrix properties data withother openhole and cased-hole loggingmeasurements.

Get near-real-time petrophysical answers to improve completion decisions.The DecisionXpress service can help youimprove production, reduce costs, andminimize risk through better, in-timedecision-making.

RXOZ

0.2 2000

3300

3250

MD

1:400 ft

CS

0 5,000(ft/h)

TENS

10,000 0(lbf)

RSOZ

DSOZ

RHOZ

1.95 2.95(g/cm3)

NPOR

0.45 0.15(p.u.)

PEFZ

0 10

eaeaAHTRT

0.2 2000(ohm-m)

AHTRX

0.2 2000(ohm-m)

AHT90

0.2 2000(ohm-m)

AHT60

0.2 2000(ohm-m)

AHT30

0.2 2000(ohm-m)

AHT20

0.2 2000(ohm-m)

AHT10

0.2 2000(ohm-m)

(ohm-m)

RHGE

2.5 3(g/cm3)

Mineralogy

0 1(lbf/lbf)

ECGR

0 200(gAPI)

SP

190 60(mV)

GDEV

10 90(deg)

HCAL

6 16(in.)

BS

6 16(in.)

Mudcake

3500

3450

3400

3350

3500

Washout

Siderite

Pyrite

Carbonate

QFM

Clay

Quality Flag Descriptions

Absent Reliable Warning Unreliable Unreliable

Mineralogy Flags

P: ECS Hardware: PhotomultiplierE: ECS Data Quality: Elemental Statistical Uncertainty

Resistivity Flags

M: MCFL HardwareX: Rxo ProcessingC: AIT Processing ChartB: AIT Borehole ConditionM: AIT Magnetic Mud

Acceleration/Nuclear Flags

A: AccelerometerN: Neutron ProcessingD: HRDD HardwareR: RHOZ ProcessingP: PEF Processing

P R D N A M B C X M E P

This presentation combines input data from the Platform Express and ECS tools with quality control flags.The flags displayed are for the most relevant hardware and processing quality-control indicators.

A

B

C

A. The AIT* Array Induction Imager Tool borehole condition flag indicates the tool was runclose to its limits. In this conductive mud environment, the 1-ft vertical resolution is affected,but the 2-ft resolution used in the DecisionXpress service is of good quality.

B. The ECS quality flag warns of increased statistical uncertainty resulting from environmen-tal effects.

C. Neutron porosity (NPOR) and density (RHOZ) are displayed on a standard limestone unitscale. Before matrix and full-environment corrections, those measurements do not overlayin clean-water zones.

Pocket

PR_03_020_0 ©Schlumberger

April 2004 *Mark of Schlumberger

Produced by Oilfield Marketing Communications, Houston.

www.slb.com/oilfield

Platform Express and ECS Tool Specifications

Platform Express Components ECS Sonde

HGNS HRMS HALS AIT-H Tool

Output Gamma ray, Bulk density, Laterolog, resistivity, Induction resistivity, Elemental relative yields,neutron porosity, photoelectric factor (PEF), spontaneous potential, spontaneous potential, dry weight elements and tool acceleration borehole caliper, mud resistivity mud resistivity lithologies, matrix

microresistivity properties Range of Gamma ray: Bulk density: 0.2–40,000 ohm-m 0.1–2000 ohm-m 600 keV–8 MeVmeasurement 0–1,000 g API 1.04–3.3 g/cm3

Neutron porosity: PEF: 0.9–100–60 p.u. Caliper: 22 in. [55.9 cm]

Vertical Gamma ray: Bulk density: 18 in. [45.7 cm] Standard: 1, 2, and 4 ft 30 in. [76.2 cm]resolution 12 in. [30.5 cm] in 6-in. [15.2-cm] borehole 18 in. [45.7 cm] [0.30, 0.61, and 1.22 m]

Porosity: 12 in. [30.5 cm] High resolution:8 in. [20.3 cm] availablein 6-in. [15.2-cm] boreholes

Accuracy Gamma ray: ±5% Bulk density: 1–2,000 ohm-m: ±5% Resistivities: ±0.75 mS/m 2% (coherence toPorosity: ±0.01-g/cm3 accuracy, conductivity or 2% standards computed)

0–20 p.u. ±1 p.u. 0.025-g/cm3 repeatability (whichever is greater)30 p.u. ±2 p.u. Caliper:45 p.u. ±6 p.u. 0.1-in. [0.25-cm] accuracy,

0.05-in. [0.13-cm]repeatability

Depth of Gamma ray: Density: 5 in. [12.7 cm] ~32 in. [~81 cm] AO/AT/AF10†: 10 in. [25.4 cm] 9 in. [22.9 cm]investigation 24 in. [61.0 cm] (varies with formation AO/AT/AF20: 20 in. [50.8 cm]

Porosity: ~9 in. [~23 cm] and mud resistivities) AO/AT/AF30: 30 in. [76.2 cm](varies with hydrogen AO/AT/AF60: 60 in. [152.4 cm]index of formation) AO/AT/AF90: 90 in. [228.6 cm]

Logging speed 3,600 ft/hr [1,097 m/h] 3,600 ft/hr [1,097 m/h] 3,600 ft/hr [1,097 m/h] 3,600 ft/hr [1,097 m/h] 1,800 ft/hr [549 m/h]Temperature rating 302°F [150°C] 302°F [150°C] 302°F [150°C] 302°F [150°C] 350°F [177°C]

500°F [260°C] (internal flask cooled using carbon dioxide)

Pressure rating 15,000 psi [103 MPa] 15,000 psi [103 MPa] 15,000 psi [103 MPa] 15,000 psi [103 MPa] 20,000 psi [138 MPa]High-pressure housing: 25,000 psi [172 MPa]

Min. borehole size 6 in. 6 in. 6 in. 6 in. 6.5 in. [16.5 cm]Max. borehole size 16 in. 16 in. 16 in. 16 in. 20 in. [50.8 cm]OD 3.375 in. [8.6 cm] 4.77 in. [12.1 cm] 3.625 in. [9.2 cm] 3.875 in. [9.8 cm] 5.0 in. [12.7 cm]

High-pressure housing:5.5 in. [14.0 cm]

Length 10.85 ft [3.3 m] 12.3 ft [3.8 m] 16 ft [4.9 m] 16 ft [4.9 m] 10.15 ft [3.1 m]Weight 172 lbm [78 kg] 313 lbm [142 kg] 221 lbm [100 kg] 255 lbm [116 kg] 305 lbm [138 kg]

† AO = 1-ft [0.3-m] vertical resolution; AT = 2-ft [0.6-m] vertical resolution; AF = 4-ft [1.2-m] vertical resolution