Interference well-test model for vertical well with double-segment fracture in a multi-well system

Abstract

Single well pressure transient analysis ignores the impact from adjacent wells, while well interference has obvious effect on the pressure response. Additionally, fracture conductivity and half-length may decrease severely, leading to non-uniform closure along fractures. The interpreted fracture half-length could be much shorter than designed half-length if this phenomenon is ignored. Besides, well interference caused by adjacent wells in multi-well system could be mistaken as boundary effect in single-well model since type curves of these two circumstances are quite similar to each other, which could bring about unrealistic results compared with geologic characteristics. Therefore, distinguishing interference effect from boundary effect while considering non-uniform fracture closure becomes a major challenge.This work proposes a new interference well-test model of vertical well with double-segment fractures (VWDSF). Each double-segment fracture (DSF) contains two fracture segments (FS) with individual length, rate and conductivity, etc. The new model allows the observation well and adjacent wells to produce at the same time, which does not influence production. Analytical solution is verified by comparing with numerical solution from Saphir, and model comparison is proposed to elaborate the significance of the novel model. New flow regimes including fracture interference flow, multi-well interference flow, interference-radial flow regime (IRFR) and system-radial flow can be observed on type curves. Furthermore, the influence of the observation well and adjacent wells on type curves are analyzed. Case study highlights the ability of the developed model in distinguishing the interference effect and boundary effect using the novel model. The proposed model provides a useful tool for addressing erroneous interpretation of pressure transient data due to non-uniform fracture closure and/or well interference.