RIASSUNTO
Abstract
The Ram-Powell Unit encompasses eight OCS leases in the Viosca Knoll Area of the Eastern Gulf of Mexico.
The blocks are located approximately 125 miles east, southeast of New Orleans and approximately 80 miles south of Mobile, Alabama in water depths ranging from 2,000 to 4,000 ft. Since the drilling of the discovery well on Viosca Knoll Block 912 in May 1985, five commercial pay sands have been logged between 5,500 and 13,500 ft subsea.
This paper describes the planning and successful execution of the highly challenging A9 extended-reach well designed as the first development of the G sand interval. G sand represents the new geological play for the field as it is approximately 1,500 ft shallower than the main reservoir horizons of the field. The well was designed as a combined exploration and development project and a fast-track completion scheme was devised.
The authors will discuss the design strategy, which focused on hole cleaning and the urgency of getting the casing to bottom immediately after drilling. The drilling and completion team employed a systematic approach to planning and execution of the well, which integrated both drilling and completion.
Along with detailing the planning and execution of the project, the authors also will detail the lessons learned, including the difficulty in distinguishing between borehole instability and hole cleaning problems when pulling out of the hole.
Introduction
The Ram-Powell Unit began production in September 1997 from a tension-leg platform (TLP). Peak total throughput of 70,700 bbl/d of oil and 252 mmcf/d of gas was achieved in April 1998. To further develop the field a three-well drilling program was developed. This required modifications of an existing MASE (minimum area self erecting) rig.
The A-9 was planned as the first well in the re-development program. The A9 well represents the latest geological play in the field as it was designed to develop the until now unexploited G sands at 25,400 ft MD. In this new drilling program, the team recognized the risk of drilling the most difficult well first. To be successful the team had to overcome issues associated with matching a new rig in a new environment and minimize problems associated with starting up a new program.
After extensive planning the well was successfully drilled and completed within the budgeted days and cost estimates.
Rig Design and Installation
Drilling a complex ERD well mandated that the rig have the personnel and equipment to meet the challenge. A MASE rig from the Shell active rig fleet was chosen for the Ram Powell program. The selection of this rig provided the following:
Experienced rig team with an established safety culture.
Track record of best-in-class performance on previous ERD wells.
A hydraulic system (3, 7500 psi mud pumps) to meet the demands of the A-9 well.
Capable of meeting the dynamics requirements for operating on a TLP.
Modifications were undertaken on the rig to allow for running and support of the drilling riser, set back 24,000 ft. of drill pipe, increase to the mud pit capacity and other fit-for- purpose upgrades. A derrick barge was used to install the skid base and the rig was installed with platform crane. The modifications and installation of the rig were completed within the projected time frame.
Well Information
G sand is a near-field exploration prospect delineated by a bright seismic amplitude approximately three miles from the Ram Powell tension-leg platform (TLP) in 3000 ft of water in the Eastern Gulf of Mexico. Pre-drill estimates of recovery volumes ranged from four to 12 million bbl of oil equivalent. Although Ram Powell field is in production since 1997 until the drilling of the A-9 well there was no history of development of the G sand interval. Craig et al1 and Lester et al2 present an overview of Ram Powell field and well design, respectively. G sand represents the new geological play for the field as it is approximately 1,500 ft shallower than the main reservoir horizons of the field.