Summary
Objective
Ultra-Deepwater drilling activity has increased dramatically in the last two years. Operations that were once exceptional and characterized by several man-years of well and operations planning, equipment qualification and contingency planning are now being done routinely several times each rig year.
DEA – 63, Floating Vessel Blowout Control, completed in the early 90’s did not contemplate operations in water as deep as we commonly operate in now. While the project did contain a good deal of information, it was not widely available or read within the industry. One reason for this was massive restructuring that continues to take place within the oil business and lack of a publication mechanism to make it available to a wide audience
We propose a project to expand DEA – 63 for application into ultra-deepwater, develop a Visual Basic / Spreadsheet based dynamic kill program for ultra-deepwater and make the document available through the Texas A&M University Press, the International Association of Drilling Contractors, or other means of publication that would best reach the intended audience as either a technical report or handbooks for end users or both.
We propose to expand on DEA – 63 in the following areas:
- Mechanical intervention – We would update the deepwater intervention methods proposed in DEA – 63 taking into account advancements made in deepwater construction since the late 80’s. We would also evaluate the hydraulic requirements for methods that have been proposed in the past now taking into account the very long sections of pipe necessary to reach the sea bed.
Additional new work would be done in the following areas:
- Bridging tendencies in ultra-deep water blowouts – Gulf of Mexico and other ultra-deepwater sediments are generally poorly consolidated. Many believe that a high rate ultra-deep water blowout will bridge and self kill. We will investigate the likelihood of this and define the parameters for evaluation of bridging including conditions with open hole drilling and cased hole completions.
- Dynamic kill investigation of ultra-deepwater blowouts – we would develop a dynamic kill model for deepwater blowouts and investigate methods and pump rates necessary to kill the blowout from the existing well bore or from one or more relief wells.
- Development of Dual Density blowout control methods – In the event that a deepwater blowout results in loss of the riser or a disconnect it may not be possible or safe to reconnect the riser and divert flow to the surface. If that is the case, dynamic kill could only be accomplished from a relief well using Dual Density mud weights. Furthermore, Dual Density drilling methods are likely to become commercially available in the next two years. It is likely that a well drilled to a formation using Dual Density methods could not be killed by a relief well using any other drilling method. Investigation of dynamic kill with Dual Density drilling will be included in the proposed study.
- Costs of intervention – We propose to develop a cost estimate template for ultra-deepwater blowout intervention.
Approach
The proposed work is a multi-year, multi-phase project and has been broken down into five separate tasks, some of which could be performed independently of each other. Tasks 1, and 2 could be performed concurrently. Except for the literature and data gathering, Task 3 cannot begin until Task 2 is sufficiently complete so that the model could be utilized to validate the methods developed in Task 3. Task 4 cannot be completed until Task 3 is nearly complete. Task 5 will be completed after Tasks 1-4 are complete. A separate budget has been submitted for each task (as well as a travel and meeting budget). Each task is described below.
These five tasks that make up the entire project will be performed in two Phases. Phase I will consist of Tasks 1 and 2, complete. The initial work (literature review and data gathering) on Task 3 will begin in Phase I. Phase II will include the completion of Task 3 as well as Tasks 4 and 5. The U.S. Department of Interior – Minerals Management Service and the Offshore Technology Research Center has funded Phase I in its entirety. Phase II funding must come from industry and other sources through GPRI.
Phase I
Task 1 – Bridging of blowouts in the GOM and tools for evaluation.
High flow rate blowouts sometimes cause the well bore to collapse and bridge. When this occurs the well will often self kill, resulting in probably the fastest and least expensive method of blowout containment. Bridging usually occurs in poorly consolidated sandstones, and reactive shales, which are common in the Gulf of Mexico. This project proposes to study the formations likely to be encountered in ultra-deep waters of the GOM to determine the conditions in which well bores will collapse and bridge. The project will also determine if there are ways in which the likelihood of bridging could be increased. We will also investigate the cases with long open hole intervals where bridging high in the hole may not be advisable because of the possibility for cross flow below the bridge.
Task 2 – Dynamic kill model for conventional and dual density Deep Water Blowouts (surface and underground) and investigation of pump rates to kill wells.
Dynamic kill models have been developed in the past, however these models may not be adequate for blowouts in water depths as great as 10,000 feet, nor are they designed to model dual density operations. A dynamic kill model will be developed which can be used for both conventional drilling and dual density operations. Both cases will have the capability of predicting kill rates for circulation through the drillstring in the blowout well as well as from relief wells. Returns will be modeled for circulation up the marine riser, choke or kill line, through seafloor pumps and return line (for dual density) all back to the surface, as well as exiting the well bore into the water column at the seafloor. The model will also have the ability to analyze underground blowouts. Modeling of underground blowouts with consideration for thief zone characteristics is not available in many current dynamic kill models.
Task 3 – Phase I – Develop blowout control methods based on Task 2 to include mechanical hookup alternatives.
During Phase I, a study will be made of the state of the art in blowout containment methods and equipment that is presently available. Data from actual blowout cases will be gathered and then used to validate the Bridging and Dynamic kill simulators developed in Tasks 1 and 2. We will begin to use the dynamic kill simulator to evaluate the hydraulic requirements needed to dynamically kill ultra-deepwater blowouts for hypothetical cases. This will be used to determine the capabilities of the simulator and identify any necessary improvements. During our study of actual blowout cases we will analyze which actions were more successful in regaining control of these blowouts.
In our search for actual blowout cases we will also gather data on ultra-deepwater kicks. From this study we will develop a “best practices” model for handling of ultra-deepwater kicks.
The results of Phase I will by catalogued and included in a Phase I report available through the MMS web site conference proceedings, and trade publications.
Deployment of Results
MMS would have in hand a useful document for evaluation of ultra-deepwater well control risk and knowledge of methods necessary for successful intervention.
Industry would have access to a document that could guide well planning, contingency plan development and ultra-deepwater blowout intervention operations should that ever become necessary.
At the completion of this project, the following deliverables will have been met.
- The industry will be provided with a study which will determine the likelihood of a well bridging during a deepwater blowout, and ways to induce bridging and the consequences of undesirable bridging that may result in cross flows below the bridge. A bridging simulator will be available to forecast bridging in blowouts. This simulator will also have the capability of forecasting sand production problems in producing wells as well as well bore stability problems during underbalanced or near balanced drilling operations.
- A dynamic kill simulator with the ability to model:
- conventional and dual density wells
- circulation paths through the a drillstring located in the blowout well and relief wells
- returns to the surface via the drilling riser, choke and kill line, seafloor pumps and return line, or returns to the ocean at the seafloor,
- and underground blowouts.
- A manual cataloging the state of the art in blowout containment equipment and methodology. This will include mechanical hookup alternatives.
- Blowout control methods for dual density wells.
- Cost estimate for deepwater intervention.
- Cost estimate for deepwater intervention.
During the project a series of forums will be held with representatives from the industry sponsors, MMS, and OTRC, as well as others with a vested interest in the results of the project.
Related Publications
Jourine, S., Karner, S L, Kronenberg, A K, Chester, F M.: Influence of Intermediate Stress on Yielding of Berea Sandstone Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract T41D-0249, 2003.
Jourine S., Schubert J.J, Valkó P.P.: Saturated Poroelastic Hollow Cylinder Subjected To Non-stationary Boundary Pressure – Model and Laboratory Test. Submitted to Gulf Rocks ’04, 6th North American Rock Mechanics Symposium (NARMS).
Oskarsen, R. T., and Schubert, J.J., “Development of a Dynamic Kill Simulator for Drilling in Ultra-deep Water,”, Presented at the AADE National Technical Conference
Jourine, S., and Schubert, J. J., “Wellbore Bridging as a Possible Alternative to Blowout Control in Ultra-Deepwater Wells,” Presented at the 2003 AADE National Technical Conference, Houston, TX. April 1-3, 2003
