Production system analysis of the Titas Gas Field

Abstract

The overall performance of any well depends on well inflow performance, downhole-conduit flow performance and surface-flow performance. The changes made in one component of the system have an overall effect on the entire system. The objective of the study is to analyze the performance of 11 gas wells in Titas Gas Field of Bangladesh Gas Field Company Limited (BGFCL), a subsidiary company of Bangladesh Oil, Gas and Mineral Corporation (Petrobangla). The effects of various parameters on overall well performance have been studied. The parameters considered are: Separator pressure, flowline size, surface chokc size, tubing size, average reservoir pressure and different reservoir parameters. The sensitivity of each parameter has been observed to identify any bottle necking or over sizing of equipment. In this study, up to date data have been used whereever available, otherwise values have been reasonably assumed. Then the individual wells have been tied in the same way as in the field and the effect of a parameter on the whole system has been observed. Nodal analysis approach has been followed in conducting the system analysis starting from the outer boundary of the reservoir to the sand face, across the perforations and completion section to the tubing intake, up the tubing string including any restrictions and downhole safety valves, the surface choke, the flowline and the separator. For this study, the software- PIPESIM for Windows was used which uses the principle of nodal analysis method. In the study, wells TT-l through TT-lO are observed to produce at optimum rate but the flowline and tubing are generally oversized. Tubing ofTT-ll is found to be restricted; using optimum size of tubing in the well significantly increases the production rate. Then, in the integrated models, it is found that change in the choke size of any well does not affect the performance of other wells. This is quite expected as all the wells are producing in the critical range of the choke.