The productivity increases that could be achieved by fracturing high permeability formations were limited by the fracture conductivity. Oil rate increases of 5- to 6-fold were typical with aggressive TSO treatments building up to 2000 psi net pressure. These fractures were successfully placed near water contacts without detrimental increases in water production.
The paper describes the techniques used in Prudhoe Bay to place small, highly conductive fractures in areas of the field where there is no fracture containment to prevent fracture growth into an aquifer.
A reservoir study to investigate the effects of fracturing close to oil water contacts is presented, together with 3D fracture modelling of fractures with no downward containment. The paper highlights the importance of spurt losses in both frac designs and minifrac analyses, when fracturing high permeability reservoirs. A simple minifrac analysis, for use with complex fracture geometries, is provided.
The fracture design methodology is presented, supported by field examples.
Author(s): SPE, SPE, A.J. Durrani, B.M. Escovedo, William Ordemann, J.A. Bickley, B.J. Tepper, and J.M. Simon, Shell Western E&P Inc.
Paper Number: SPE 24872