JOINT-INDUSTRY PARTNERSHIP TO DEVELOP A HOLLOW SPHERE DUAL-GRADIENT DRILLING SYSTEM
Maurer Technology Inc. (MTI) formed a joint-industry partnership to fund the development of a hollow sphere dual-gradient drilling (DGD) system. Phase I consisted of collecting, compiling, analyzing, and distributing information and data regarding a new DGD system for use by the oil and gas industry. Near the end of Phase I, DOE provided funding to the project that was used to conduct a series of critical follow-on tests investigating sphere separation in weighted waterbase and oilbase muds. Drilling costs in deep water are high because seawater pressure on the ocean floor creates a situation where many strings of casing are required due to the relatively close spacing between fracture and pore pressure curves. Approximately $100 million have been spent during the past five years on DGD systems that place pumps on the seafloor to reduce these drilling problems by reducing the annulus fluid pressure at the bottom of the riser. BP estimates that a DGD system can save $9 million per well in the Thunderhorse Field and Conoco estimates it can save $5 to $15 million per well in its deepwater operations. Unfortunately, previous DGD development projects have been unsuccessful due to the high costs ($20 to $50 million) and reliability problems with seafloor pump systems. MTI has been developing a simple DGD system concept that would pump hollow glass spheres into the bottom of the riser to reduce density of the mud in the riser. This eliminates the requirement for seafloor pumps and replaces them with low cost mud pumps, shale shakers, and other oilfield equipment that can be operated on the rig by conventional crews. A $1.8 million Phase I joint-industry project funded by five service companies and three operators showed that hollow spheres could be pumped well, but difficulties were encountered in separating the spheres from a polymer mud supplied by Halliburton due to the high viscosity of this mud at the low shear rates encountered on oilfield shale shaker screens. As a result, an excessive amount of this polymer mud flowed across the screen with the beads instead of through the screen. At the completion of the Phase I project, it was concluded that the hollow sphere system would not work effectively with the polymer mud tested. ExxonMobil and Shell engineers proposed that additional sphere separation tests needed to be conducted with weighted oilfield waterbase and oilbase muds to determine if the DGD system would work with these muds. The DOE agreed to provide a $200,000 grant for these tests. The DOE-funded tests, described in this report, showed that the spheres could be pumped with conventional oilfield centrifugal and triplex mud pumps and separated effectively from both oilfield waterbase and oilbase muds using conventional oilfield shale shakers and hydrocyclones. As a result of the success of these DOE tests, this DGD system is ready for full-scale field testing, first on land wells and later in the offshore environment. Maurer Technology Inc. is currently proposing a Phase II project to oil companies to further develop this DGD concept. This project would be funded by four to eight operators. If Phase II tests are successful, Noble plans to commercialize this system with a service company partner that will market and operate the DGD system on Noble's and other drilling contractors' rigs.
- Research Organization:
- Maurer Technology Inc. (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC26-02NT41641
- OSTI ID:
- 833216
- Resource Relation:
- Other Information: PBD: 1 May 2003
- Country of Publication:
- United States
- Language:
- English
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