IDENTIFYING OPPORTUNITIES FOR HYDRAULIC FRACTURE OPTIMIZATION IN A MATURE AND LAYERED RESERVOIR USING A NOVEL CORRELATION INDEX

Hydraulic fracturing has been widely applied in the low to medium permeability reservoirs in Elk Hills with varying degrees of success. Infill wells are completed across several layered sandstone formations in contact in the wellbore. Distinct sand zones are selectively or jointly stimulated and commingled for production with a downhole artificial lift installed. Since 1998, various changes and improvements to treatment designs and placement techniques have been implemented in other to improve the fracture stimulation response. It involved using different fracturing fluids, changes to proppant sizes and concentrations, accelerating residual gel flowback, acquisition of relevant fracture diagnostic and significant changes to treatment and completion methodology to maximize the effective fracture conductivity. Post frac analysis showed the dominant concerns that negatively affect stimulation response are related to reservoir depletion across the reservoirs and in delineating fault blocks. As a result, optimization efforts have focused on the mitigation and prevention of formation damage.

From a study of the frac database since 2004, a  relative fracture treatment index is proposed for optimizing production response that incorporates some elements of the treatment that potentially affects damage cleanup of residual treatment gels. This paper evaluates the degree of correlation of the  index with well productivity and discusses the potential for identifying refrac opportunities across well groups or reservoir sections using the alpha (symbol for alpha) index.