Step Change in Hydraulic Fracturing Methodology by Analyzing Clastic Gas Reservoir Field Experience to Achieve Production Enhancement

Abstract

The clastic non-associated gas reservoirs are encountered in one of the Saudi Arabian oilfields. There is a wide variation in permeability in this Devonian age formation, varying from tight rocks with 0.1 md or less to more than few Darcie's in highly unconsolidated sandstones. While the prolific areas are easily producible at sustained high gas rates by conventional drilling and using sand control completion mechanisms, the relatively tighter areas require hydraulic fracturing to sustain commercial flow rate. During the last 10 years, the field A focused on exploiting gas reservoirs is being developed with vertical or S-shaped wells, and completed using a monobore tubular assembly. Proppant fracturing treatments are routinely conducted in multiple stages along the vertical wellbore. Fracture treatment parameters are adjusted over time by the introduction of different fracture fluids to enhance stability and avoid premature screen out. Proppant flow back measures were taken with the use of resin-coated proppants. A large database was developed on stimulation treatments and results that allowed conducting a detailed analysis to understand the behavior and effect of hydraulic fracturing trends on the reservoir performance to optimize the design parameters and further increase reservoir potential. This paper documents the analysis of the pre- and post-fracture treatment data, production analysis and thorough evaluation of petrophysical and geomechanical measurements from this massive database of 10-year long operational period. This study shows that there is a room to improve fracturing treatments and fluid chemistry and recommends a step change in the well stimulation strategy by modifying some existing technologies and also applying novel technologies that have been carefully studied and approved using laboratory and field trial testing. The results from the application of this new strategy are presented in the paper using actual examples.