AIR HAMMER DRILLING Submitted by…

SACHIN KULSHRESHTHAINT.B.TECH(APE)+MBA(UAM)

R-270307030SEM-VIII

Ideal Candidate for Air Drilling • Long wellbore sections with Minimal

Formation Pressures

• Medium - Hard Formations w/ Low ROP

• Deviation Problems due to High Formation Dip Angles

• Lost Circulation Problems

• Formations that have Minimum Water Influx

• Water Sensitive Formations (Shales) are time sensitive to sloughing.

• Hydrocarbon zones are typically Gas bearing.

Advantages of Air Drilling

Faster R.O.P. (2-5 times faster than on Mud).

• Improved Deviation Control (light WOB).

• Minimal Formation Damage in Production section.

• Effective Pressure Control through Lost Circulation Zones.

• Detection of Low Pressure Zones.

• Faster return of drilled cuttings (formation evaluation).

• Overall Lower Cost per Foot.

Most Common Air Drilling Applications

• Hard Rock Drilling where ROP is less than 15 ft/hr using mud.

• Areas that have Deviation Problems with conventional BHA’s and use light WOB.

• Lost Circulation Problems.

• Pay-Zones that are sensitive to Formation Damage w/mud.

Taking another look at the risk profile for air drilling in presence of hydrocarbons

shows the minimum oxygen concentration required for combustion of

methane is 12% by volume at sea level.

The autoignition temperatures for aliphatic hydrocarbons commonly produced. The ignition temperature tends to decrease with the number of carbons in the chain. 

Table shows constituents of air.

Component MolecularMass (gm)

VolumePercent

Partial Pressure(mmHg)

Nitrogen 28.013 78.06 593.4

Oxygen 31.998 20.95 159.2

Argon 39.948 0.93 7.1

Carbon Dioxide 43.999 0.03 0.2

28.95 (avg) 99.99% 759.9

Table shows the physical properties of Alkane family compounds.

Compound

ChemicalFormula

AIT(oF)

FlashPoint (oF)

BoilingPoint (oF)

LEL (%) in Air21% O2

UEL (%) in Air21% O2

Minimum OxygenConcentration (%)

Methane CH4 999 -306.4 -258.7 5 15 12

Ethane C2H6 959 -211 -127.8 3 12.4 11

Propane C3H8 871 -155.2 43.8 2.1 9.5 11.5

n-Butane C4H10 761 -101.2 31.1 1.8 8.4 11.5

n-Pentane C5H12 496 -56.2 97 1.5 7.8 12

n-Hexane C6H14 433 -9.4 155.7 1.1 7.5 12

n-Heptane C7H16 433 26.6 209.1 1.1 6.7 11.5

n-Octane C8H18 428 57.2 257.0 1 6.5 N/A

n-Nonane C9H20 403 87.8 303.4 0.8 5.6 N/A

n-Decane C10H22 406 114.8 345.4 0.8 5.4 N/A

n-Dodecane C12H26 399 165.2 421.2 0.8 N/A N/A

n-Tetradecane

C14H30 235 210.2 485.7 0.6 4.5 N/A

When atmospheric air is compressed, the local temperature increases because of the compression of the air molecules in a confined space. This is known as adiabatic compression

Best Drilling Practices for Air Hammer Drilling• Air Volumes VS Annular Velocity

– Minimum A.V. of 3000 feet/min. (Angel’s curves).– Optimum A.V. of 5000+ feet/min. (Field experience).– 30% additional air volume suggested for Misting and/or Directional applications.• Hammer Configuration

– Choke size should be determined to operate 350psidifferential across the hammer.– Hammer with heavy piston has been found to be faster in misting and/or Hard-Rock applications.– Hammer with lighter piston but higher frequency hasbeen found to be faster in medium to soft rock whiledusting.

Type of drilling techniques

Drilled depth (m)

Name of well

Company name

Rig employed

Hole size

Time taken (days)

Cost Employed

Conventional drilling

60 Jabera#2

ONGC ONGC RIG

26’’ 143 15 lacs/day

Air hammer drilling

255 Nohtha ONGC (on contract to Shiv Ganga Drillers)

24’’ 33 3.4 crores

CASE STUDY

SHIV GANGA DRILLERS AT A GLANCE IN CONTEXT WITH MADHYA PRADESH DRILLING…

SHIV GANGA DRILLERS PVT LTD..

OWNER : ONGC,FRONTIER BASIN

OPERATOR : SHIVGANGA DRILLER’S PVT LTD

SITE OF WORK : NOTHA (JABALPUR)

START DATE : 30TH OCT.2010 (MOBILIZATION)

FINISH DATE : 2ND DEC.2010 (DE-MOBILIZATION)

DEPTH DRILLED : 255 MTRS OF 24’’

PILOT HOLE : 250MTRS

DAYS FOR COMPLETE OPERATION : 32 DAYS

COMPRESSORS RUNNING HOURS : 198 HRS

RIG RUNNING HOURS : 500 HRS

Air Hammer Drilling -- Arkoma Basin What has be done? • 17 1/2” Intermediate (TVD 60’ – 600’): – BP (Red Oak) -- Arkoma Basin – Year 2001 using Rig Air (2400 SCFM) • Average ROP = 30 - 40 ft/hr for hammer; • 20 ft/hr on Mud with RC bits – Year 2002 - 2004 using 3400 SCFM of Air Volume • Air Hammer with Diamond Hammer Bit drills to

Casing Point • Average ROP = 75 ft/hr. • World Record = 104 ft/hr by H & P # 189 (Top

Drive) • Cost Savings 3/4 days = $ 10k – $ 15k

Air Hammer Drilling -- Barnett Shale What has been Done ? • 8 3/4 Production Hole (Vertical Section) – Objective: Drill Production Hole from 1500’ to KOP @ 6500’ – 2003 -- using Mud and Roller Cone Bits (some on

motors) • 3 - 4 trips for bits; ROP = 40 - 50 ft/hr average • 6 - 8 days depending upon deviation problems – 2004 -- using Air Hammer with 2400 - 3000 SCFM of Air • 1 bit / 1 trip; 80% of jobs; 3 days; Avg. ROP = 85+ ft/hr • 2 bit / 2 trip; 20% of jobs; 4 days; Avg. ROP = 100+ ft/hr – Increased Air Volumes and Pressures increases ROP but Bit life has been lowered. – Performance Drilling = Cost Per Foot (Guarantee) – Cost Savings 2 - 4 days = $ 30k – $60k – Deviation issues are also being overcome

Conclusion Drilling with air continues to be a very popular method of

drilling. There are many advantages to drilling with air, especially in hard rock, non-hydrocarbon bearing and non-water producing lithology.

The question for every prudent engineer, operator and contractor should be, “Is it technically appropriate to continue to drill with air when hydrocarbons are suspected of being present in the open wellbore?”

. From 1994-2003, the upstream oil and gas sector has had the dubious distinction of having a fatality rate 8.5 times higher than the average for all industries within the United States. There were 8 very specific recommended strategies described in SPE 94416 to modify our existing safety track record

We recommend that air drilling be used for performance enhancement purposes in only non-hydrocarbon bearing lithology.Ideally, air drilling should cease just prior to exposing any hydrocarbon production zones. Once a hydrocarbon zone is penetrated or suspected of being penetrated, air drilling should cease and another drilling fluid should be used.

In organizations that apply air drilling techniques, engineering and safety departments should make special efforts to frequently inform, educate and train personnel on safe air drilling operations and make that information available to them on a continuing basis.

 

Thankyou