Progress Reports: June 2006 December 2005
APPLICATION OF DUAL GRADIENT TECHNOLOGY TO TOP HOLE DRILLING
BACKGROUND: In 1996, three competing projects began aimed at mitigating many of the problems encountered in ultra-deepwater drilling, including the narrow window between pore pressure and fracture gradient, high riser loads, high deck loads, and high costs of drilling fluids, etc. These three projects were conducted by Shell on a Submersible Pump System, Transocean on DeepVision, and Hydril on the SubSea MudLift Drilling system in joint industry programs to develop the technology known as dual gradient drilling. All three projects achieved a dual gradient by placing a rotating diverter on top of the BOP stack, which diverted the mud returns from the annulus to a set of seafloor pumps. These pumps then circulated the mud and cuttings back to the rig via an external return line. The marine riser was filled with seawater rather than mud as in the conventional case. After an enormous amount of time, energy, and money were spent to develop dual gradient technology, a test well was drilled in the Gulf of Mexico by Hydril and the members of the SubSea MudLift Drilling Joint Industry Project in 2001.
In all three of these industry projects, the dual gradient drilling package was designed to be emplaced after surface casing was set to manage the window between pore pressure and fracture pressure, thus, extending the length of open hole sections between casing strings, and minimizing mud costs. Although these systems lowered the riser loads with a water filled riser, the packages were still designed to be employed on fifth generation drilling vessels using the existing riser system. Because these projects focused on deeper portions of the wells, massive, elaborate, and complex systems were developed.
One dual gradient drilling application that has not been fully studied is the potential benefit of utilizing this technology in the top hole portion of the well.
OBJECTIVE: The objective of this study is to evaluate the application of dual gradient drilling in the top hole portion of a well. This would allow conductor and surface casing to be set deeper (possibly with a smaller third generation floater), which would allow safer drilling of the intermediate hole. We believe a Top Hole Dual Gradient (THDG) drilling package would improve drilling safety by providing a mud circulating system which has limited pressure control while drilling in a managed pressure drilling mode certain hazards seen in shallow marine sediments. Some of the hazards a THDG drilling system can minimize include methane hydrates, shallow gas, and shallow water flows. THDG systems can lead to better technology than the current “pump and dump” process currently utilized in top hole drilling. An additional benefit of this technology is setting conductor and surface casing deeper in HTHP deep gas well applications as well as in ultra deep water applications. By focusing more attention on the top portion of the wellbore, smaller lighter and simpler drilling equipment and facilities could be used to drill deeper water wells.
This evaluation would be initiated through an MMS-funded Phase I to describe the potential benefits of DGTH drilling and initiate work on key components. Industry engagement and support would be solicited for Phase II and III to (1) obtain industry technical and operational input and (2) funding to complete the project. Phases II and III would be entirely funded by industry. The MMS would be able to fully participate in these Phases in exchange for funding Phase I and providing results to the industry. It is envisioned that this evaluation project would lead to a subsequent effort, Phase IV, to design, build, and field test a DGTH system.
This project represents an effort by the MMS to advance and encourage research that has the potential to become part of the Best Available and Safest Technology (BAST) for offshore oil and gas development in Federal waters.
INTRODUCTION: When starting a well, the operator needs to address and mitigate the shallow subsurface geotechnical hazards that threaten the safety of the drilling unit prior to installation of the blowout preventor (BOP). The purpose of the THDG package is to maintain the required borehole pressure in a riserless (i.e., conventional drilling riser not used) drilling mode, using a rotating head with a mechanical seafloor pump and mud return line to the ship to:
• Mitigate various pressure related geotechnical hazards at shallow penetration depths (e.g., pressured water and gas sands) by imposing the optimum circulating pressure and mud rheology to improve wellbore stability and hole cleaning without increasing mud weight;
• Mitigate formation fracturing and mud loss by controlling the pressure on the wellbore, using a seafloor pump either as an annular choke (i.e., to increase wellbore pressure) or as a mud lift pump in riserless mode (i.e., to eliminate the hydrostatic pressure effect of the mud column that would be in the riser);
• Reduce the seafloor pollution and loss of mud caused by the “dump and pump method;” and
• Reduce the number and size of casing strings required during drilling operations (i.e., by extending casing setting depths to cover problem formations with fewer casings).BENEFITS TO MMS & INDUSTRY: MMS and the industry will have the results of a preliminary engineering study on the use and packaging of dual gradient drilling for top hole applications that could potentially improve safety by mitigating shallow gas, shallow water flows, limited margin between fracture and pore pressure gradient, and gas below the hydrate cap or sealing zone (when drilling through hydrates) in the Gulf of Mexico. This technology could also minimize the environmental impact of the current “pump and dump” practice while drilling conductor and surface holes.
By using a THDG drilling package for riserless oil and gas exploration and development drilling, a smaller and less expensive rig can be used, drilling risks can be reduced, and time on site and rig costs could be decreased. By decreasing time on location, and not using a conventional drilling riser, smaller and less expensive vessels can be used to perform the same work, resulting in lower exploration costs. Industry will also benefit by avoiding the requirement to circulate large volumes of mud onto the seafloor to handle geotechnical hazards and water flows in the top hole.
DEPLOYMENT OF RESULTS: The results of the project will be conveyed to the MMS and the petroleum industry through M.S. Theses, and Ph.D. Dissertations, TAMU-MEEN design project report, conference presentations, and publication in trade journals. The MMS and industry supporters of the project will also receive project reports and an overall final report that will tie the individual theses and design efforts together and provide a comprehensive documentation describing all project results.
ANTICIPATED NUMBER OF PHASES: 3
PROJECT PLAN FOR PHASE I (2005-2006):
Scope and Plan: Phase I includes the following Tasks:
1. Benefits of THDG – TAMU-PETE will analyze the benefits of THDG drilling over conventional riser and riserless (pump and dump) drilling. Even though some of this work has been performed, a complete study has not been made, nor have the benefits been fully discussed in industry publications. As part of our literature review, TAMU-PETE intends to gather information on the advantages of published THDG cases, assess the results, and prepare conclusions and recommendations. The results will be included in the final report to the MMS. We will also analyze how dual gradient technology may benefit the industry while drilling in known methane hydrate areas, artificially charged shallow marine sediments, and deep HTHP gas wells on the shelf. Along with this analysis, TAMU-PETE will develop THDG procedures that will mitigate these problems and will determine specifications for the equipment to implement proposed procedures. We will utilize the TAMU well control simulator and dual gradient hydraulics to study various kick scenarios that may be encountered while drilling these areas. TAMU-PETE will also use the simulator to test proposed well control procedures.
2. Minimum THDG Equipment Requirements – TAMU-PETE will determine the minimum equipment requirements for the THDG package, including any necessary pressure containment equipment. After defining the problems that can be mitigated with a THDG package, TAMU-PETE will provide comment on the specifications of the THDG package to TAMU-MEEN.
3. Define Mud Circulating System – We will define the mud and circulating system requirements. TAMU-PETE will determine the mud density range and rheological properties to be utilized with the THDG package as well as the hydraulic and power requirements of the circulating system. TAMU-PETE will be involved in designing the entire mud circulating system, including surface mud pump requirements, drilling fluid properties, and mud cleaning equipment.
4. Conceptual Engineering Design of Pumping Equipment – TAMU-MEEN will begin conceptual engineering design of the equipment required to conduct THDG drilling, including (1) the option of using only the dual gradient pump package in a balanced drilling mode and (2) the option of drilling with a minimal (two barriers) BOP stack below the dual gradient pump package has been completed. An industry consultant will be employed to refine the preliminary design for well control and drilling operations.
5. Conceptual Engineering Design of the Riser System – TAMU-PETE will begin conceptual engineering design of the riser (mud return line and power supply for a dual gradient pump package) and associated running procedures for drilling riserless. TAMU-MEEN working with a consultant will perform the preliminary engineering design of the riser.
6. Well Control and Drilling Procedures – TAMU-PETE will begin to develop well control and drilling procedures for THDG drilling. TAMU-PETE will develop drilling and well control procedures for THDG drilling in parallel with the equipment design and testing. These procedures will include contingencies for handling shallow water flows, hydrates, shallow gas, and artificially charged formations below mudline sediments. TAMU-PETE will test these procedures with the dual gradient hydraulic and drilling simulator developed at Texas A&M University as part of the Subsea Mudlift Drilling JIP.
7. Solicit Industry Support for Phase II and III – Project results available from the first 9 months of the project will be used as the basis for soliciting industry support through a JIP, an organization such as the TAMU-PETE’s Chrisman Institute, or other arrangement. Aside from the benefits of industry engagement and input, the industry will fund Phases II and III. Initial meetings with industry should be completed by 6 months and formal solicitation of support should be completed 3 month before the end of Phase I in order to avoid/minimize any delay in continuing the project with Phase II and III. It is envisioned that the project team would hold a meeting with industry as part of the solicitation process, and that the MMS will participate in that meeting to indicate their interest and support for this project.
8. Report & Presentation on Current Phase - A report documenting the progress and results completed in Phase I will be prepared. A presentation will be given to MMS staff in the GOM Regional Offices in New Orleans.
Anticipated Milestones & Results: By the end of Phase I, we will have completed tasks 1, 2, 3, and 7, and have made substantial progress on tasks 4, 5, and 6.
Deliverables for Phase I: A status report summarizing progress and interim results will be submitted by February 1, 2006, and a Final Phase I report will be submitted by September 1, 2006. The Final Phase I report will document the developments, results, and conclusions for this phase, which will include a complete report on the benefits of Dual Gradient Drilling in the Top Hole Section of the well. It will also include the results of the minimum equipment requirement task, as well as the definition of the mud circulating system. The project team will also make a presentation of the Phase I results to MMS staff in New Orleans.
PROJECT PLAN FOR PHASE II (2006-2007):
Scope of Work: A steering team will be formed to provide the project team with a input, guidance, and advice on project milestones, results, and plans though periodic meetings throughout Phases II & III. The steering team members will include representatives from industry supporters and the MMS. Phase II will include work on the following Tasks:
4. Conceptual Engineering Design of Pumping Equipment – The project team will complete the conceptual engineering design of the pumping equipment required to conduct THDG drilling,
5. Conceptual Engineering Design of the Riser System – The project team will complete the conceptual engineering design of the riser system (mud return line and power supply for a dual gradient pump package) and associated running procedures for drilling riserless.
6. Well Control and Drilling Procedures – TAMU-PETE will complete the well control and drilling procedures for THDG drilling. TAMU-PETE will develop drilling and well control procedures for THDG drilling in parallel with the equipment design and testing.
8. Report & Presentation on Current Phase - A report documenting the progress and results completed in Phase I will be prepared. A presentation will be given to MMS staff in the GOM Regional Offices in New Orleans.
9. Risk Analysis – TAMU-PETE will begin a risk analysis on the equipment and the procedures designed for this project. TAMU-PETE will perform a thorough HAZID and/or HAZOP on all drilling and well control procedures developed for this project to maximize the probability of success. When the risk associated with a procedure is too great, we will re-write or modify the procedure to mitigate the risk to an acceptable level. If the mitigation results in more than a minor change in equipment design or procedure, the risk analysis will be performed again. If requested, TAMU-PETE will also be involved in the risk analysis on the equipment designed for this project.
Anticipated Results: By the end of Phase II, we will have completed tasks 4, 5, and 6, and have made substantial progress on task 9. A report will be prepared to document the progress and results completed in Phase II. The project team will also make a presentation of the Phase II results to MMS staff in New Orleans.
PROJECT PLAN FOR PHASE III (2007-2008):
Scope of Work: Phase III will include work on the following tasks:
9. Risk Analysis - The project team will complete the risk analysis on the equipment and the procedures designed for this DGTH drilling system.
10. Develop Plan for Phase IV - The project team, in consultation with the project steering team, will develop a plan for the path forward for Phase IV to design, build, and field test a DGTH system, and solicit induststies support to fund and conduct the field test.
11. Final Report - The project team will prepare the Final Report on the Project. The report will provide a comprehensive documentation of all results completed in Phases I-III. Write final report. During the final year, the project team, MMS, and industry sponsors will determine the path forward and funding opportunities to design, build and shop test the prototype equipment. The project team will prepare the Final Project Report. The report will provide a comprehensive documentation of all results completed in Phases I-III and the recommended path forward.
Anticipated Results: The final product produced by TAMU-PETE will be a detailed design of the mud circulation system and written manuals that will define, describe, and discuss the drilling and well control procedures required for THDG drilling. In addition, TAMU-MEEN will produce a preliminary engineering or conceptual design of the dual gradient riser and associated running equipment and procedures, all based upon preliminary layouts of the dual gradient top hole drilling package. The project team will have completed plans for a follow-on Phase IV project to build, and test a complete system, and a plan to solicit industry support to pursue this field test as a Joint Industry Project.
PRINCIPAL INVESTIGATORS AND OTHERS INVOLVED IN THE PROJECT:
PI’s: Jerome J. Schubert, PhD., P.E C. Steve Suh, PhD - Texas A&M University
Others: Mr. Charles Peterman – Independent Consultant
DATE: May, 2006
Project Title: Application of Dual Gradient Technology to Top Hole Drilling
MMS Project: 541 TO Number: 39317
PI: Jerome Schubert
COTR: S. Buffington
Estimated Completion Date: Phase I - September 2006 (Project term is 12/31/2006)
Project Description: The objective of this 3 Phase study is to evaluate the application of dual gradient drilling in the top hole portion of a well. The objective of Phase 1 (MMS funded) is to describe the potential benefits of DGTH drilling and initiate work on key topics. Phase 2 and 3 (industry funded) would complete a conceptual design and risk analysis for the DGTP system, and develop a plan for a Phase 4 to build and field test a DGTH system. Industry funding is needed to ensure the necessary engagement and input needed to progress this concept for field testing and eventual application.
Progress: Phase I includes the following tasks. The task objectives and progress are noted.
1. Benefits of THDG – TAMU-PETE will analyze the benefits of THDG drilling over conventional riser and riserless (pump and dump) drilling. Even though some of this work has been performed, a complete study has not been made, nor have the benefits been fully discussed in industry publications. As part of our literature review, TAMU-PETE intends to gather information on the advantages of published THDG cases, assess the results, and prepare conclusions and recommendations. The results will be included in the final report to the MMS. We will also analyze how dual gradient technology may benefit the industry while drilling in known methane hydrate areas, artificially charged shallow marine sediments, and deep HTHP gas wells on the shelf. Along with this analysis, TAMU-PETE will develop THDG procedures that will mitigate these problems and will determine specifications for the equipment to implement proposed procedures. We will utilize the TAMU well control simulator and dual gradient hydraulics to study various kick scenarios that may be encountered while drilling these areas. TAMU-PETE will also use the simulator to test proposed well control procedures.
This task is completed and documented in an MS Thesis.
2. Minimum THDG Equipment Requirements – TAMU-PETE will determine the minimum equipment requirements for the THDG package, including any necessary pressure containment equipment. After defining the problems that can be mitigated with a THDG package, TAMU-PETE will provide comment on the specifications of the THDG package to TAMU-MEEN.
Complete.
3. Define Mud Circulating System – We will define the mud and circulating system requirements. TAMU-PETE will determine the mud density range and rheological properties to be utilized with the THDG package as well as the hydraulic and power requirements of the circulating system. TAMU-PETE will be involved in designing the entire mud circulating system, including surface mud pump requirements, drilling fluid properties, and mud cleaning equipment.
Substantially complete.
4. Conceptual Engineering Design of Pumping Equipment – TAMU-MEEN will begin conceptual engineering design of the equipment required to conduct THDG drilling, including (1) the option of using only the dual gradient pump package in a balanced drilling mode and (2) the option of drilling with a minimal (two barriers) BOP stack below the dual gradient pump package has been completed. An industry consultant will be employed to refine the preliminary design for well control and drilling operations.
Three teams completed and reported conceptual design of the subsea pumping equipment in the MEEN graduate design course. The best system has been determined and the students continued through the spring semester to refine the conceptual design. Their final report will be available shortly.
5. Conceptual Engineering Design of the Riser System – TAMU-PETE will begin conceptual engineering design of the riser (mud return line and power supply for a dual gradient pump package) and associated running procedures for drilling riserless. TAMU-MEEN working with a consultant will perform the preliminary engineering design of the riser.
See Task 4.
6. Well Control and Drilling Procedures – TAMU-PETE will begin to develop well control and drilling procedures for THDG drilling. TAMU-PETE will develop drilling and well control procedures for THDG drilling in parallel with the equipment design and testing. These procedures will include contingencies for handling shallow water flows, hydrates, shallow gas, and artificially charged formations below mudline sediments. TAMU-PETE will test these procedures with the dual gradient hydraulic and drilling simulator developed at Texas A&M University as part of the Subsea Mudlift Drilling JIP.
The Well Control Procedures have been tested and the results are included the MS thesis discussed in Task 1.
7. Solicit Industry Support for Phase II and III – Project results available from the first 9 months of the project will be used as the basis for soliciting industry support through a JIP, an organization such as the TAMU-PETE’s Chrisman Institute, or other arrangement. Aside from the benefits of industry engagement and input, the industry will fund Phases II and III. Initial meetings with industry should be completed by 6 months and formal solicitation of support should be completed 3 month before the end of Phase I in order to avoid/minimize any delay in continuing the project with Phase II and III. It is envisioned that the project team would hold a meeting with industry as part of the solicitation process, and that the MMS will participate in that meeting to indicate their interest and support for this project.
We have begun soliciting industry support for this project with some interest from the industry.
8. Report & Presentation on Current Phase - A report documenting the progress and results completed in Phase I will be prepared. A presentation will be given to MMS staff in the GOM Regional Offices in New Orleans.
The final report will include an executive summary with the MS thesis and MEEN design reports bound together.
Publications & Reports:
M.S. Thesis:
1. “Top Hole Drilling with Dual Gradient Technology to Control Shallow Hazards”, Brandee Elieff, August, 2006.
Conceptual design reports:
1. “Embodiment Design Report: Top Hole Dual Gradient,” Chris Dharmawijatno, Mahesh Sonawane, and Chris Krueger, December 9, 2005.2. “Development of Top Hole Dual Gradient Drilling System for Deep Sea Drilling that Provides Unobstructed Path for Mud Return,” Sukesh Shenoy, Amol Dixit, A.S. Nandagopalan, December 9, 2005.
3. “Top Hole Dual Gradient System: Submersible Mud Removal Unit,” John Guinn, Gerald Thomas, Lauren Wiseman, December 9, 2005.
Conference Presentations:
1. “The Feasibility of Top Hole Drilling with Dual Gradient Technology,” Brandee Elieff, Dr. Jerome J. Schubert, IADC/SPE Managed Pressure Drilling and Underbalanced Operations Conference, April 2006.
(Drilling Contractor magazine has asked Brandee Elieff to write an article based on her presentation.)2. “Top Hole Dual Gradient Drilling System: A strategic Approach Towards Deepwater Drilling”, Sukesh Shenoy, Amol Dixit, A.S. Nandagopalan, Dr. Steve Suh, Dr. Jerome J. Schubert, IADC/SPE Managed Pressure Drilling and Underbalanced Operations Conference, April 2006.
Other papers for Technical Journals and an SPE textbook chapter are also being completed for submission.
DATE: December, 2005
Project Title: Application of Dual Gradient Technology to Top Hole Drilling
MMS Project: 541 TO Number: 39317
PI: Jerome Schubert
COTR: S. Buffington
Estimated Completion Date: Phase I completion date 08/31/2006
Project Description:
Phase I includes the following Tasks:1. Benefits of THDG – TAMU-PETE will analyze the benefits of THDG drilling over conventional riser and riserless (pump and dump) drilling. Even though some of this work has been performed, a complete study has not been made, nor have the benefits been fully discussed in industry publications. As part of our literature review, TAMU-PETE intends to gather information on the advantages of published THDG cases, assess the results, and prepare conclusions and recommendations. The results will be included in the final report to the MMS. We will also analyze how dual gradient technology may benefit the industry while drilling in known methane hydrate areas, artificially charged shallow marine sediments, and deep HTHP gas wells on the shelf. Along with this analysis, TAMU-PETE will develop THDG procedures that will mitigate these problems
and will determine specifications for the equipment to implement proposed procedures. We will utilize the TAMU well control simulator and dual gradient hydraulics to study various kick scenarios that may be encountered while drilling these areas. TAMU-PETE will also use the simulator to test proposed well control procedures.2. Minimum THDG Equipment Requirements – TAMU-PETE will determine the minimum equipment requirements for the THDG package, including any necessary pressure containment equipment. After defining the problems that can be mitigated with a THDG package, TAMU-PETE will provide comment on the specifications of the THDG package to TAMU-MEEN.
3. Define Mud Circulating System – We will define the mud and circulating system requirements. TAMU-PETE will determine the mud density range and rheological properties to be utilized with the THDG package as well as the hydraulic and power requirements of the circulating system. TAMU-PETE will be involved in designing the entire mud circulating system, including surface mud pump requirements, drilling fluid properties, and mud cleaning equipment.
4. Conceptual Engineering Design of Pumping Equipment – TAMU-MEEN will begin conceptual engineering design of the equipment required to conduct THDG drilling, including (1) the option of using only the dual gradient pump package in a balanced drilling mode and (2) the option of drilling with a minimal (two barriers) BOP stack below the dual gradient pump package has been completed. An industry consultant will be employed to refine the preliminary design for well control and drilling operations.
5. Conceptual Engineering Design of the Riser System – TAMU-PETE will begin conceptual engineering design of the riser (mud return line and power supply for a dual gradient pump package) and associated running procedures for drilling riserless. TAMU-MEEN working with a consultant will perform the preliminary engineering design of the riser.
6. Well Control and Drilling Procedures – TAMU-PETE will begin to develop well control and drilling procedures for THDG drilling. TAMU-PETE will develop drilling and well control procedures for THDG drilling in parallel with the equipment design and testing. These procedures will include contingencies for handling shallow water flows, hydrates, shallow gas, and artificially charged formations below mudline sediments. TAMU-PETE will test these procedures with the dual gradient hydraulic and drilling simulator developed at Texas A&M University as part of the Subsea Mudlift Drilling JIP.
7. Solicit Industry Support for Phase II and III – Project results available from the first 9 months of the project will be used as the basis for soliciting industry support through a JIP, an organization such as the TAMU-PETE’s Chrisman Institute, or other arrangement. Aside from the benefits of industry engagement and input, the industry will fund Phases II and III. Initial meetings with industry should be completed by 6 months and formal solicitation of support should be completed 3 month before the end of Phase I in order to avoid/minimize any delay in continuing the project with Phase II and III. It is envisioned that the project team would hold a meeting with industry as part of the solicitation process, and that the MMS will participate in that meeting to indicate their interest and support for this project.
8. Report & Presentation on Current Phase - A report documenting the progress and results completed in Phase I will be prepared. A presentation will be given to MMS staff in the GOM Regional Offices in New Orleans.
Note: Phases II and III will be conducted as a JIP.
Progress:
1. Benefits of THDG We have made substantial progress on listing the advantages of Top Hole Dual Gradient. The literature review is substantially complete and will be part of in at least one MS thesis and will be summarized in a portion of a chapter in a new SPE Drilling Textbook.
2. Minimum THDG Equipment Requirements – TAMU PETE has substantially completed the definition of the required Equipment and provided this information to TAMU-MEEN.
3. Define Mud Circulating System – We have begun this.
4. Conceptual Engineering Design of Pumping Equipment – TAMU-MEEN has had three teams of three working on the conceptual design of the subsea pumping equipment. The results of this will be included in final reports submitted to Dr. Steve Suh as part of the requirements for his MEEN graduate design course. The best system will be determined and at least three students will continue in the spring semester to refine the conceptual design.
5. Conceptual Engineering Design of the Riser System – See Task 4
6. Well Control and Drilling Procedures – Not begun
7. Solicit Industry Support for Phase II and III – We have begun soliciting industry support for this project.
8. Report & Presentation on Current Phase – Reports are being written for the preliminary design by the MEEN students. Two abstracts have been accepted for presentation at the IADC/SPE Manage Pressure Drilling and Underbalanced Operations Conference in April, 2006
Publications & Reports:
See Task 8