Publications

A deepwater gas well in the West Seno Field, offshore Indonesia was completed with a frac-pac to mitigate problems with sand and fines production. Since its initial production in December 2004, completion efficiency has been tracked with seven pressure buildup tests in two years. The pressure derivative preceding the infinite acting radial flow regime shows characteristics of an induced fracture, that to-date, have not been reported for a frac-pack well in the literature. All pressure build-up tests were analyzed to determine fracture length, skin, boundary effects and reservoir pressure. In order to verify the diagnosis, these parameters were then used in a nodal analysis to calculate gas production rate, which agrees very well with field data. The mechanical skin damage component of the total skin was shown to be increasing with time. This was considered to be plugging of the gravel pack due to fines entrainment. As a result of this finding, the gravel size was increased in future frac packs to facilitate the production of formation fines through frac pack. Detailed surveillance monitoring of this early development well allowed optimization of frac- pack completion designs for future wells in the field. Reservoir pressures derived from PBU tests were used in material balance to calculate original gas in place. Separately a 3D reservoir simulation was conducted to match the history of gas production rate, reservoir pressure, and tubing head pressure. After successfully matching these parameters, the 3D model was then used to investigate the potential of various workover options. This study demonstrates integrating PBU, material balance, nodal analysis, and 3D modeling is an effective method for reservoir surveillance and workover planning.