Abstract
Estimating ultimate recovery using information from the boundary-dominated flow regime is not practically achievable in unconventional (low permeability) resources since the time required to reach this flow regime is quite large (typically years). In response to this problem, the ultimate objective of this research project is to estimate ultimate recovery of horizontal wells with multistage fractures using only information obtained after wells have reached interference between adjacent fractures. I have taken the first step towards achieving this objective by simulating the boundary condition in heterogeneous reservoirs using the similarity between pressure diffusion and electromagnetic and ray wave propagation. Estimating ultimate recovery more accurately will enable us to optimize well spacing and reduce the number of unnecessary wells drilled, saving capital investments of many millions of dollars.
I have implemented the mechanism of electromagnetic and ray wave propagation in pressure diffusion models to simulate boundary conditions that affect flow in the reservoir. When a light wave reaches the interface of two media, some light is reflected back to the same media while the remainder is transmitted into the other media. A ‘pressure wave’ behaves in a similar way when it reaches a boundary in the reservoir. Therefore, we have incorporated reflection and transmission coefficients into the drawdown solution of the diffusivity equation. We used a channel reservoir to validate our approach. The pressure transient analysis solution obtained using our method matches well with the true solution generated by the pressure transient software Ecrin. We can use the accurate early time match to estimate important reservoir properties including porosity and permeability. The accurate middle time pressure information can be transformed into rate information and then used to estimate ultimate recovery.
