Abstract

The South Lhok Sukon (SLS) 'A' & 'D' gas reservoirs are located southeast of the Arun field in North Sumatra, Indonesia. The SLS 'A' reservoir was discovered in 1972 and SLS 'D' was discovered in 1991. The Peutu Limestone is the productive horizon in both reservoirs, and contains very lean gas.

Based on an integrated geophysical, geological, and engineering analysis, reservoir simulation models were developed for each field. The simulation models were used to evaluate development options. In this paper, we describe the results of production well optimization studies using the simulation models. The well locations were designed to take advantage of geologic features such as facies distribution and high permeability/porosity layers.

Recent improvements in drilling technology have resulted in wider use of horizontal wells for field development. The advantages of using horizontal wells versus vertical wells in South Lhok Sukon was investigated and horizontal wells were selected because of their higher deliverability. Because horizontal well performance is strongly dependent on the vertical/horizontal permeability ratio, the effect of Kv/Kh ratio was examined. Other variables such as well location, horizontal section length, and well trajectory were investigated. The effects of skin factors and tubing size were also determined. As a result of well optimization, the total number of wells and field development costs were reduced, resulting in improved project economics.