The Semberah field is located onshore on the Mahakam delta, East-Kalimantan, Indonesia. It is operated by VICO Indonesia. Reservoirs in this field consist of multi-layered sandstones deposited in a complex fluvio-deltaic environment. After more than 30 years of production, this field has reached a mature stage. Most of the remaining reserves are locked in low permeability reservoirs, on which conventional techniques have not been very effective in depleting the reserves.
These low-permeability reservoirs require technology innovations to economically produce the reserves. A comprehensive approach was taken by a multidisciplinary team of geologists, reservoir engineers, drilling and completion engineers to assess options for technology application and identify candidate reservoirs for low-perm zone development. Several technologies were considered including horizontal wells, radial jetting, and hydraulic fracturing. Of the technologies applied, horizontal well was proven as the most effective technique to increase productivity of these low-perm reservoirs. One horizontal well was successfully executed and intersected 867 ft of lateral section into the target reservoir. The well was put on production giving exceptional results. For comparison, the well increased the gas production rate of the target reservoir from 1 MMSCFD using conventional techniques to 15 MMSCFD using horizontal drilling. Currently, the horizontal well is still producing. Cumulative production has reached in excess of 7 BCF after a period of 6 years. Other technologies, such as radial jetting and hydraulic fracturing, were also applied but they recover moderate-size gas reserves with less successful results. Lessons-learned were captured and several elements of improvement were identified for future application.
This paper illustrates the lessons learned in searching for the fit-for-purpose technology application to unlock gas reserves in low-permeability reservoirs in a geologically complex environment such as the Semberah field.