Abstract: Genesis: Innovation for Deepwater Development

Young, W. Scott - Chevron U.S.A. Production Co.

During the summer of 1998 Chevron installed the world?s first drilling and production spar at a 2600 foot water depth location in the Gulf of Mexico. First oil is expected by the end of 1998. Genesis, the project designation for the Green Canyon Blocks 205, 160, and 161 deepwater development, is designed to produce 55,000 BOPD and 72 MMSCFD of gas.

In 1993, a multidisciplinary team was formed to evaluate development options. The multidisciplinary team included geologists, reservoir engineers, drilling engineers, and facility engineers as well as project management personnel, economic analysts, environmental and regulatory advisors. Personnel were drawn from the business unit as well as from Chevron?s Technology Companies, and JV owners. Data from 3-D seismic surveys, electric logs, and well tests were incorporated into a complete geological model. Oil samples acquired during delineation drilling were analyzed to determine reservoir fluid properties. A reservoir simulation model was created to assess the performance characteristics of several development scenarios. Nineteen development options were studied which included subsea wells producing to a semi-submersible or FPSO, TLP?S, compliant towers, and spars. For each option, technical feasibility, constructability, and operability were evaluated. Production forecasts and cost estimates were considered, covering a wide range of outcomes, to yield expected value economics. After a rigorous evaluation, and based on relative NPV, OPEX, ease of operability, and a strategic fit for future deepwater opportunities, the spar was found to be the best alternative.

Some of the main drivers affecting the selection process were complex reservoirs, downhole intervention capability, dual completions, use of a leased drilling rig, and ability to optimize facility layout with respect to safety and operations.

Surface trees were found to offer several advantages over subsea trees because frequent well maintenance was expected (paraffin was found in oil samples collected during delineation drilling), several recompletions would be required over the life the field (Genesis will eventually produce from 27 separate reservoir zones), and dual completions would save drilling costs and reduce well slot requirements on the platform (Genesis will have five wells with dual completions and it was felt there would be more risk with dual completions in subsea wells). Surface stack drilling was also found to be advantageous because of reduced drilling time.

New-build facilities were preferred over conversions because of the ability to design for purpose (topsides equipment layout, operations, and safety) rather than force-fit or do major vessel modifications.

The Genesis spar data is shown on the figure. It will support a maximum operating topsides load of 19,500 tons. The spar will be moored on location by 14 taut leg lines, consisting of a combination of 5-1/4 inch wire and 5-1/4 inch chain, which are pinned to the seafloor with steel piles. The 22 risers terminate at the seafloor on the circumference of a 140 foot circle (20 foot spacings). By a combination of skidding the drilling rig and manipulating the mooring lines, the drilling rig can be located over any of the wellslots and any wellslot can be located over its corresponding seafloor location.

Chevron has employed many ?best practices? techniques to both focus the project execution and reduce risks. We believe a key to success is to treat each contributor as a stakeholder and to foster a feeling of membership in the expanded Genesis team. Techniques such as project execution planning, value engineering, constructabilitv reviews, benchmarking, process hazards reviews, and technical specialist involvement have all been employed to understand project risks, manage cost and schedule, and to provide a better opportunity for the best possible project outcome.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil