Practical Well Testing Analysis Considerations in Heterogeneous Sandstone

Abstract

Declining reserves in conventional gas reservoirs, high energy demand and the evolution of technology are all encouraging oil and gas companies to consider the feasibility of exploiting large reserves trapped in heterogeneous and tight gas reservoirs. In general, successful results in tight gas depend on identifying the sweet spots as well as an efficient hydraulic fracturing treatment for it to be commercially viable. Nevertheless, in order to evaluate the success of the stimulation job, the reservoir and hydraulic fractures properties need to be quantified. The pressure build-up analysis is a classical tool that is widely used in the petroleum industry to gain more insight into the reservoir by studying the pressure variation before and after stimulation. In order to be able to determine skin and reservoir flow capacity, the reservoir must reach infinite acting radial flow, which is characterized by a flat stabilization on the pressure derivative. This paper highlights some of the extensive pre and post stimulation pressure build-up results on heterogeneous and tight gas Sarah sandstone found in the northwest of Saudi Arabia. The analysis shows different behaviors in terms of reservoir response between a series of build-up in different conditions including openhole, cased hole and post-stimulation test analysis on the same well. A systematic approach was used to connect between these responses using integrated reservoir data.