DEA-162 – DeepTrek JIP for Advancing Deep, Hard Rock Drilling Performance through Controlled, Full-scale Laboratory Drilling Experiments with Aggressive Bits and Specialized Fluids

DEA Project Summary [162]

Date Submitted: February 20, 2007

Technical Area:  Exploration

Sponsor:  BP / Robert Coolidge /  281-366-5916 / robert.coolidge@bp.com

Title: “DeepTrek JIP for Advancing Deep, Hard Rock Drilling Performance Through Controlled, Full-scale Laboratory Drilling Experiments with Aggressive Bits and Specialized Fluids”

Principle Investigator:    Homer Robertson, TerraTek, a Schlumberger company

Business Impact:

A critical cost in future deep oil and gas recovery is the cost to drill a well.  This cost is dominated by the rate of penetration (ROP) that becomes increasingly important with increasing depth.  Improving the technology of drilling and increasing the ROP will lower the cost to drill a well.  This improves the economics of deep exploration and development, potentially increasing drilling activity, increasing production and supply, lowering the cost to the consumer and improving the economy.

For domestic operations involving hard rock and deep oil and gas plays, improvements in drilling penetration rates are an opportunity to reduce well costs and make viable certain field developments. These regions include the Rocky Mountains, Tuscaloosa trend, Arbuckle formation, Anadarko basin, and several other areas. An estimate of North American hard rock drilling costs is in excess of $1,200 MM. Thus potential savings of $200 MM to $600 MM are possible if penetration rates are doubled [and assuming bit life is reasonable]. The net result for operators is improved profit margin as well as an improved position on reserves.

Some of the challenges of drilling in deep and hard formations include;

  • Rock strength increases with increased depth. Also seen are increased shale plasticity and bit balling tendencies.
  • High overbalance (Borehole – Pore Pressure) resulting in chip hold down.
  • High mud solids, high density, increased viscosity, lower spurt-loss fluids in Deep Wells
  • Rig and operational limitations i.e. low hydraulics, bit wear, friction losses, differential sticking, lost circulation, etc.

Figure below shows example time – depth curves for example Tuscaloosa wells

presented by BP’s John Shaughnessy to the Department of Energy, 2001

(times below 18,000 ft Measured Depth are long)

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Figure below shows average ROP vs. bottomhole pressure;

presented by BP’s Richard H. Reiley to the Department of Energy, 2002

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Industry partners and the U.S. Department of Energy (DOE) successfully completed benchmark testing of advanced diamond bits and high pressure/high temperature (HP/HT) drilling fluids at high pressures.  The results of this testing identified factors limiting ROP performance at great depth, and the development of drilling fluid systems and bit design philosophy to significantly improve drilling performance.  Benchmark results match very well with data from target field applications.  This project was part of the DOE Deep Trek program.  Thirty-seven full-scale tests of 6 inch bits were conducted at wellbore pressures greater than 10,000 psi. Results from high-pressure tests with water and base oil showed very high ROPs are possible before mudding up.  When drilling through hard sandstone penetration rates can drop 70 to 80% on switching to a weighted mud.  These data emphasize the importance of mud technology in high-pressure applications.  Performance of polycrystalline diamond compact (PDC) bits showed in many cases substantial improvements over roller cone insert and impregnated bits.   Substantial improvements in penetration rate were achieved with a low solids weighted fluid (cesium formate), a Manganese based weighting material and an alternate sized and distributed weighting material.  Cuttings from Carthage marble and Mancos shale appear to be compressed agglomerates of fine particles and Carthage marble cuttings had low compressive strengths.

The study has concluded that opportunities for improvements in both bit design and smart HP/HT drilling fluids are possible. While rock properties change continuously with pressure, the cutting mechanisms at great depths change much more dramatically. Changes in bit design and mud composition, using next generation technology, will be evaluated in Phase II testing.  The significance of improved ROP for deep oil and gas plays include opportunities to reduce well costs and improve the economics of deep exploration and development plays. The net result for operators is cost reduction as well as an improved position on reserves.

The test matrices and example results for the Deep Trek project are shown below:

DeepTrek Phase 1 Benchmark Test Matrix

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DeepTrek Phase 2 Advanced Fluids and Bits Test Matrix

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Example of Phase 1 Benchmark ROP Results Above

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Example of Phase 2 ROP Improvements Above

Technical Impact:

The proposed project will be an extension of the recently completed Deep Trek testing program which has demonstrated potential for marked improvements in deep drilling performance through aggressive bit design and use of specialized drilling fluids.  The testing would involve 6” diameter bits, drilling fluids in the 11 to 16 ppg range, 10,000 psi borehole pressure, 11-12,000 psi confining pressure and overburden stress and flow rates up to 300 gpm.  The rock types will be the same as used in the Deep Trek project including Crab Orchard sandstone, Carthage marble and Mancos shale, but also could included other challenging formations i.e. a balling shale like Pierre 1 shale.  The compressive strength versus confining pressure of these three rocks are shown below:

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The impact of the proposed extension of the industry and DOE sponsored Deep Trek project will be the testing and evaluation of a number of potential drilling fluid and bit improvements nominated for testing by the operator and service company participants by leveraging resources of a number of companies who are facing the same drilling challenge.  A good example of what can be identified and developed with such a program is the DEA 90 project on deep drilling in soft, balling shale with water-based fluids conducted at TerraTek in the later 1990’s and early 2000’s.  In this project, mechanisms related to bit design and fluid properties were identified which cause bit balling and slow ROP, bit and drilling fluid improvements of reduce bit balling and fluid additives (ROP enhancer to dramatically improved penetration rate.  Also, whereas the Deep Trek project was supported by one service company, who supplied bits, fluids and supplemental pumping services, the proposed Deep Trek JIP would be expanded to included several service companies.

Methodology:

Along with the full-scale laboratory drilling test results i.e. ROP versus WOB, RPM. Flow Rate and Borehole Pressure (simulated depth), the cuttings recovered will be analyzed to determine cutting mechanisms, fluid/rock interaction, etc.  In addition, Mechanical Specific Energy based on ROP, torque, WOB, etc. will be calculated and analyzed to determine drilling efficiency.

Deliverables:

A kick and initial planning meeting and at least one planning meeting part way through the project will be held in Houston or Salt Lake City to nominate bits and fluids for testing and to review results.  After completion of the project, a report will be prepared and a lesson’s learned meeting will be held.  There will be a three year confidentiality period from the date of the issuance of the report.

Start Up Date: January 1, 2008

Project Duration:  12 months (8 months preparation, 2 months testing, 2 months Analysis and reporting)

Project Cost: Minimum of $700,000 in cash and in-kind (7 participants) which could include four operators at 2 tests each and three service companies at 1 test each or a total of 11 tests

Cost per Participant:

  • Operators participation fee will be $100,000 cash (can nominate two high pressure drilling tests)
  • Standard service company participation fee will be $50,000 cash plus $50,000 in-kind for supply of bits and drilling fluids (can nominate one high pressure drilling test)
  • Special service company participation fee will be $0 cash plus $50,000 in-kind for supply of bits and drilling fluids and $50,000  in-kind for supply of supplemental pumping capacity of 150 gpm  at 11,000 psi for a period of 8 weeks (can nominate one high pressure drilling test)
  • Note: It is possible for an operator to nominate a bit or drilling fluid from a service company who is not a participant in the Deep Trek JIP, but the non-participating service company would not   receive the test results on there product

Comments:                   This is a new proposal