Indonesian Operator's First Field-Wide Application of Intelligent-Well Technology -- A Case History

Abstract

Abstract The first successful field-wide application of intelligent-well completion technology has been used in Indonesia to commingle " free energy?? from an overlying gas cap to support production from underlying oil reservoirs that typically have a high water-cut. Previously, the wells in this offshore field had been developed as conventional gas-lift completions that used gas supplied from outside the platform. The application of an " auto gas-lift?? (AGL) concept using intelligent well technology removed the capital equipment associated with conventional gas lift completions as well as the conventional downhole completion gas-lift equipment. This innovative technology provided added value from:Elimination of well intervention (for gas-lift operations using slickline).Acceleration of first productionReduction of capital expenditures (eliminated compressor package and subsea pipeline)Capability to set the gas lift at the deepest point of the well without angle limitation.Enhanced operational safety. Additional value may be realized from additional wells as they are completed and brought on-line. This paper discusses the candidate selection challenges as well as the design criteria for these auto-gas-lift intelligent wells. Specifically, the challenges have to consider the following:With an AGL intelligent well, production of the gas is uncertain and will change with timeEquipment specifications must be suitable for the range of performance of the gas and oil reservoir, the fluid composition, and the reservoir pressures. These factors all had to be taken into account when designing the system. Results to-date will illustrate the operational success of this application as well as the value added to the completions. Introduction The KE38 field is in the East Java Basin about 50-km off the northern coast of Madura Island, Indonesia (see Figure-1). Water depth averages approximately 190-feet in this block. The reservoir is composed of reef-carbonate structures within the Kujung formation. The predominant geological structure in this field has several domes (see Figure-2) with a relatively large gas-cap support. The oil columns are between 60 and 300 ft with 500 ft of gas cap on average and under-lying water. TVD of the gas-oil contact is 4500 to 5000 ft SS. Porosity of the oil rim ranges from 18 to 26%, and permeability ranges from 20 to 100-md. The reservoir is normally pressured, and the productivity is fairly consistent at between 5 and 20 bbl/day/psi. Maximum bottomhole pressure and temperature are 2200 psi and 195º F. The oil is a slightly waxy crude of 35 degrees API. Given that these wells are nearly saturated, initial production of the wells is with natural flow; however, the flowline pressure is high (up to 900 psi). These wells would require artificial lift in the initial stage of operation to kick the well and maintain certain gas/liquid ratio (GLR) to optimize the produced oil rate. Traditionally, conventional gas lift completions had been used in other fields to produce wells. There were some issues, however, that often complicated production. The timing for installation of a conventional gas-lift surface system can create significant delays that result in deferred production and incapability to optimize oil production. In addition, the capital costs associated with the surface equipment (compressor package and subsea pipeline) was significant.