Samarang Field - Seismic To Simulation Redevelopment Evaluation Brings New Life to an Old Oilfield, Offshore Sabah, Malaysia

Abstract

Summary Samarang field is a 35 year-old oilfield offshore Malaysia that was initially developed by Shell beginning in 1975. The field was relinquished to Petronas Carigali Sdn Bhd (PCSB) in 1995, which continued field operations and were able to significantly reduce the production decline rates. PCSB also transformed the field into a producing hub, allowing development of two small adjacent fields by reducing the required capital costs. However by 2003, the field was in trouble with production declining and reserves dwindling, suggesting field abandonment was on the horizon. Beginning in 2004, PCSB outsourced a major redevelopment evaluation to a multi-disciplinary, international consulting team. They maintained control by using internal expertise to peer review and assist the team's progress throughout the evaluation and at key milestone meetings. This process allowed PCSB to leverage their own organization's skills while using new technology tools employed by the team. The evaluation included a complete review of all static data, literally a seismic to simulation study approach, employing virtually every subsurface discipline in an attempt to unlock the field's remaining value. The results were full-field static and dynamic models covering the entire field and allowing an integrated redevelopment plan. This plan consists of numerous infill producers and selective application of enhanced oil recovery. In addition, several near-field exploratory targets were identified. Field redevelopment is currently being implemented in a phased approach including ongoing production enhancement,sidetracking of idle wells to updip positions,addition of new well jackets for additional development wells, andselective injection into the larger reservoirs with relatively lower primary recovery. The evaluation will provide dividends for years to come with expected doubling of current production and extension of field life for another 15 years. Field Development History and Background Figure 1 shows that the Samarang Field is located offshore Sabah, East Malaysia, about 45 miles (72 km) northwest of the Labuan Gas terminal. The field surrounds a shallow reef with an water depth of 30 feet (9m). Figure 2 summarizes the field's production and development history. Shell was the initial operator and relinquished the concession to PCSB in April 1995. The field was developed in phases with the initial phase including the larger "A" and "B" drilling platforms, separate producing platforms at A, B, and C, and well jackets at C, D, and E. Subsequent development included well jackets at F and G. An additional well jacket "H" was planned by Shell for the east flank development, but was not implemented in 1986 because of low reserves potential and low oil prices. Key dates in the field's development history are as follows:Discovery: 1972 By Sm-1Field Development: 62 Wells (1975-1979) In Smdp-A,B; Smjt-C,D,E with first oil in June 1975Revisit I (86/87): 12 Wells (Smjt-F,G) And 20 S/T on Smdp-A, B and Smjt-C,D,ERevisit II (91/93): 27 Wells S/T, Three Wo and Two New In Smdp-A, B; Smjt-C, D, FPCSB Begins Operating: 1st April 1995Revisit III (97/98): 3 S/T, 1 Hhp Gas and Five New Wells In Smjt-D, F And G.B Revisit (2002): 2 S/T (Sm 52 And Sm 57) and One Recompletion (Sm 42)