Performance of a Pilot Cyclic Steam Stimulation Project in Kuwait

Abstract

Abstract The heavy oil sand reservoir of Kuwait containing a viscous, low API oil occurs at a shallow depth of about 422 feet subsea. Its reservoir temperature and pressure are generally low because of the shallow depths involved. The heavy oil reservoir has not been produced till now by the primary techniques. Primary recovery is expected to be low mainly due to lack of a natural driving mechanism. Various studies were made to find out ways and means to recover the heavy crude oil from the shallow deposits in Kuwait. The viscosity, temperature behaviour of Kuwait heavy oil is such that its viscosity is reduced by a factor of more than 100 when the temperature is increased to 300° F which suggests that the oil might be produced successfully with thermal recovery processes. Other favourable conditions for such a process are the shallow depth of the accumulation and the relatively high oil saturation. In view of their size and favourable characteristics, Kuwait's heavy oilfields are obvious candidates for the application of thermal recovery methods. It was concluded that injection of limited amounts of steam might be a very effective method for stimulation of heavy-oil wells. To obtain an early answer on the suitability of thermal process a pilot project of four wells for steam stimulation was initiated in an area near light oil production facilities. This helped in transportation of produced crude. The other favourable factors for selecting the pilot area are: Net pay thickness is the highest in the known area, The oil viscosity is moderate compared to other areas, Nearer to fresh water station. This is required as water needs to be transported by road tankers. The pilot project was initiated with simplest design and was handled with in-house expertise with minimum input from outside consultants, to achieve the following objectives: To determine the applicability of thermal recovery process for Kuwait's heavy oil deposits, To determine optimum steam injection rates, To observe reservoir response under different conditions of steam injection, To obtain information for future implementation of large scale project, To gain operating experience under local conditions and to determine problem areas. The first steam injection was started in September 1982. This paper describes the performance until the end of September 1986. The operating practices and well performances are discussed in some detail. In view of the favourable results obtained so far, steam soak projects have been expanded considerably since the start of this project. Presently another pilot of the same size as the one under discussion is underway. Further extension in the two pilot areas is being programmed.