Parameters evaluation of fault-karst carbonate reservoirs with vertical beads-on-string structure based on bottom-hole pressure: Case studies in Shunbei Oilfield, Tarim Basin of Northwestern China

Tarim Basin newly discovered the fault-karst carbonate reservoirs, which are formed by large-scale tectonic fault activities and multiple-stage karstification. Four kinds of mediums coexist in including large cave, vug, fracture matrix. The fractures interconnect with caves series to form vertical beads-on-string structure, is most common connection pattern reservoirs. To provide a well test method for evaluating this type work firstly presents multi-fracture-region multi-cave-region physical model simplifying structure. We consider four proposed model, caves, small vugs, high-angle rock regions mainly contain fracture, vug matrix mediums. cave medium. corresponding mathematical also developed, flow obeys Darcy’s law, while assumed obey free flow. Furthermore, gravity taken into account because along direction. Then typical regimes analyzed sensitivity analysis conducted on crucial parameters. Results indicate that (a) feature structure curves storage linear alternately appear; (b) will exhibit unit-slope pressure derivative existence different from inter-porosity vugs (slope ≠ 1); (c) effect could lead curves, can be regarded as closed boundary peculiar sense; (d) difficult observed about 2-weeks duration real application. Finally, two cases Shunbei Oilfield interpreted illustrate practicability feasibility method.