Recently, several Russian oil-producing companies have started to implement various technologies for stimulation of horizontal wells. Due to significant vertical permeability anisotropy of Western Siberia oil reservoirs, hydraulic fracturing treatments seem to be an effective method of production acceleration and sometimes a method of production enhancement.
In this paper, a comprehensive analysis of horizontal wells fractured from 2005–2006 in the Western Siberia oilfield is presented. This paper will discuss a list of criteria for successful candidate selection, suggest some statistical relationships for post-fracturing production forecasting, and show important factors that affect long-term performance. A new fracture treatment design optimization approach was developed on the basis of the best field practices and results of this investigation.
Simulation studies for testing the obtained results were performed using a multiphase flow reservoir simulator and a pseudo-3D fracture simulator. Three types of studies were investigated: (1) "base" cases representing horizontal well production without fracture treatments, (2) "real" cases, a study of treated well performance, and (3) "ideal" cases, which represented a modeling of horizontal well performance for treated wells on the basis of the developed design optimization approach. The impacts of some important factors—such as reservoir pressure decline in drainage zones on long-term, post-treatment production—were estimated using matched "real case" sector models. Refracture cases were also considered. Comparison of well performance for those cases enabled the estimation of long-term production increases resulting from fracturing treatments and potential incremental production increases expected from implementation of the new design approach for the Western Siberia oil field.
Results from this program resulted in new candidate selection criteria, methods for improving the accuracy of post-treatment production forecasting, and a suggested fracture design optimization approach. These important developments can help maximize long-term performance of the horizontal wells in this Western Siberia oil field and consequently can increase output for the operator from that asset.