Hydraulic Fracturing Optimization Restores Development Prospectives in Challenging Environment of the Rostashinskoe Oilfield, Orenburg Region.

摘要

Orenburg region is a part of the Volga-Urals basin and it is represents the most difficulty for development and simulation. The Rostashinskoe is one of the fields of the Pervomaysky group and it is developing since 80th of the XX century. Main producing horizons of the field are Devonian age formations: Afoninsky (DV), Vorobievsky (DIV) and Ardatovsky (DIII) formations. Uniqueness of the Pervomaysky reservoir is very light oil with portion of light weight hydrocarbons (65-70%). Oil traps of the Pervomaysky region Devonian formations are normally formed by one side faulting mechanism. Whole area of these oilfields is now covered by 3D seismic indicating traps relations to a series of regional faults scattered from east to the west. Apart from main regional faults Pervomaisky fields have quite a big number of smaller low-amplitude faults, both conductive and sealed. Presence of this faults significantly inputs into field development strategy. DIII formation of Rostashinskoe field is represented by two sandstone sub layers DIII-1 and DIII-2. Big number of faults and pinch out zones are establishing high degree of formation heterogeneity both vertically and laterally across the field. As a consequence of heterogeneity Rostashinskoe has a lot of difficulties with proper water flood and fracturing modelling in field development cycle. As a result, reserves are being recovered unequally across the field.