Application of Long Leg Horizontal Wells for Increasing Oil Recovery in Mature Oil Fields in Middle Ob Basin Area

Ivanov, Valentin¹, Mark Robinson², Alexander Bilinchuk³ (1) Shlumberger, Data and Consulting Services, Calgary, AB (2) Shlumberger, Data and Consulting Services, Megion, Teatralny Proezd 2, Russia (3) OAO “Slavneft”, Megion, Teatralny Proezd 2, Russia

The sharp increase of the oil prices in late 2003 promted most of the Russian oil pro­ducers to find ways to increase production from their mature properties. This was the case for OAO “Slavneft”, which controls a few large fields in the Middle Ob basin. The fields have been under development for the last 30-40 years, have multiple Cretaceous and Jurassic clastic reservoirs and low amplitude dome like structures. In most of them the formation pressure has been kept at initial levels with simultaneous infield water injection. Based on the analyses of the existing geological and production data detail 3D static geological mod­els were created in order to identify the most promising areas of the reservoirs containing significant residual oil. Long leg (up to 800 m) horizontal wells were placed with high pre­cision in the most promising zones of the reservoirs. In cases when geological model was somewhat ambiguous a pilot section was drilled prior to drilling the horizontal section of the well. Thank to the new advances of the in MWD the wells were placed in vertical window of 1-1.5 meters with measured debt reaching up to 3.6 km. The wells were completed open hole with lowering of slotted liner into the horizontal section. The presentation will provide 5 detail case studies.