This paper summarizes the process and technology employed by Esso Production Malaysia, Inc. (EPMI) to drill five Extended Reach Directional (ERD) wells in the recently completed Tabu-B drilling campaign.
The primary focus of the paper is the four step well planning and implementation process used by EPMI to drill the Tabu-B ERD wells. Through implementation of this process, EPMI drilled to record measured depths and horizontal displacements for the Malaysian Sector of the South China Sea using conventional, readily available drilling technologies and previously contracted drilling equipment and services.
This four step well planning and implementation process illustrated with actual examples and results from the Tabu-B drilling program, is presented for use as a generally applicable archetype for technically, operationally and economically successful drilling operations.
ESSO Production Malaysia Inc. (EPMI) is one of the major Production Sharing Contractors to PETRONAS (National oil company of Malaysia). The Offshore Division Drilling Section is the custodian of all development drilling activities conducted in the Malay Basin of the South China Sea for EPMI.
The Tabu field is one of the twelve fields drilled and developed by EPMI to date. It is located in the southeastern part of the Malay Basin, approximately 200 kilometers east of Kerteh (Fig. 1). It is an oval-shaped east-west trending anticline of approximately 26 square kilometers. Two major north-south trending normal faults separate the field into East, Central and West fault blocks. Water depth at the field is approximately 64 meters.
The Tabu field was discovered in October 1978 and field development was initiated in February 1986 with the commencement of a drilling program from the Tabu-A platform. Tabu-A development drilling was confined to the East Fault Block of the Tabu field. The Tabu-B development drilling program commenced in November 1995, utilizing the Tioman Tender-2, barge tended, platform drilling rig to develop the West and Central Fault Blocks as well as the underdeveloped areas of the East Fault Block. Economic exploitation of reserves ranging from the East Fault Block to the far western edge of the field, combined with the relatively shallow (1500-1700m) true vertical depths of the reservoirs, dictated use of high angle (in excess of 70 degrees), long reach wells from a centrally located platform. A total of 26 wells were drilled from the Tabu-B platform, of which five were Extended Reach Directional (ERD) wells. Fig. 2 presents the wellbore configuration and directional profile for a typical Tabu-B ERD well. The Tabu B-23 well drilled in January of 1996 is the deepest measured depth and longest horizontal displacement well drilled to date in Malaysia.
The drilling program and reservoir development challenges presented at EPMI's Tabu field are commonplace in today's petroleum industry. The pursuit of lower drilling costs and development of marginal resources in many cases results in the drilling of Horizontal or ERD wells. The industry's general definitions of an ERD well include:
Wells having horizontal displacements greater than twice the well true vertical depth, yielding inclination angles in excess of 63.4 degrees.
Wells which approach the limits of what has been achieved by the industry in terms of horizontal displacement.
High angle, directional wells that approach the capabilities of the contracted rig.
The Tabu-B ERD wells are most accurately described by definition 3., above. Fig. 3 presents a plot of well horizontal throw versus true vertical depth. These plots describe the industry's ERD achievement envelopes circa 1983 and currently (1st quarter 1996).