Cost-effective Time Lapse Seismic Based on Direct Transmitted P-waves for Monitoring Sagd Heavy Oil Production

Abstract

The purpose of seismic experiments was to develop a cost-effective seismic monitoring technology for a shallow heavy oil reservoir driven by SAGD. A permanent buried seismic monitoring system was deployed at one of oil sand bitumen reservoir within Cheremshan-Barstrick group of heavy oil fields, Tatarstan (Russia). It consisted of a network of measuring wells. A heat-resistant geophone was placed in each well at a depth of several meters below the base of oil sands reservoir. Field experiment included base and two monitor surveys performed during the year. To control seasonal variations of near surface elastic properties of formation a surface low channel geophone array centered relative to the wellhead of the measuring well was used upon survey. A quantitative interpretation based on time lapse direct transmitted P-wave inversion was used to determine temperature changes in reservoir conditions caused by steam injection and production. To validate seismic results, maps of ray velocity difference between base and first monitoring as well as first and second monitoring surveys were compared with temperature logs of wells-producers. They showed good correlation and had no contradictions. We concluded that the developed seismic acquisition and the workflow have sufficient sensitivity for mapping changes in reservoir conditions.