Well completion is a critical interface between the productive formation and the wellbore. The optimization of well completion to improve the production performances of horizontal wells in a heterogeneous carbonate reservoir is always a challenge. Carbonate reservoir of an offshore field located at south-east of well-known Mumbai High is extremely heterogeneous. This reservoir has a thin oil-rim which is the the key target for horizontal drain-hole placemnt. Segmented completion is used to address this lateral heterogeneity and to avoid water-breakthrough with enhanced oil production. The present study is focussed on an effective drain-hole compartmentalization using a robust work-flow in a rational and timely manner.
A methodology has been adopted using a set of well-logs in several horizontal drain-holes. Apart from basic open- hole logs (gamma-ray, resistivity, density and neutron measurements), borehole sonic imager derived results have been integrated with resistivity micro-imager analysis, which helped in isolation of heterogeneous zones. Formation slowness were extracted and used for rock-mechanical property determination. Stoneley waveform derived analysis in association with cross- dipole derived shear anisotropy results helped in swell-packer placements and segmented completion. In addition, advanced sonic analysis derived radial profiling results are also incorporated for successful placement of swell-packers by avoiding altered zones. A detailed quantification of secondary porosity and connectedness in addition with other formation-textural analysis has been incorporated from micro-resistivity imager data.
The result shows the success of swell-packer placement for segmented completion. The integrated solution, using basic and advanced well-log interpretation, was carried out within a few hours of the wireline logging for effective completion design in all the study wells. A cumulative oil production of 6000 BOPD with 5- 6% water-cut was achieved from five such wells in the same field using this methodology of completion optimization and production enhancement.