Oil Production from Low Resistivity, Thinly Bedded Middle Sands of Lower Goru, Lower Indus Basin, Pakistan

Abstract

 The Lower Goru sandstone of Cretaceous age has long been contributing considerable volumes of hydrocarbons towards Pakistan’s Oil and Gas production from the Indus Basin. The work included in this paper, demonstrates the oil discovery from thin bedded,low resistivity sands which apparently did not indicate presence of hydrocarbon’ from quick look evaluation of open hole logs. Moreover,there were no hydrocarbon shows during drilling. RFT (Repeat Formation Tester) also indicated water.
Detailed interpretation of logs response (porosity from the true resistivity Rt) indicated the presence of hydrocarbon. RFT was repeated but similar results were obtained. This was attributed to the limitation of RFTin thin beds reservoirs. Considering the RFTdata as misleading, it was decided to trust the results of detailed open hole logs. On perforation, these sands produced 600 BOPD (barrel oil per day).
This work concludes that the RFT data may be misleading due to limitation of gauge and depth imprecision in thin beds. A detailed open hole logs interpretation and careful analyses of RFT data are required in low resistivity, thinly bedded reservoirs. It is suggested that Wire line formation testers having pump out facilities and optical fluid analyzer may provide better results in such environments.