Fault-Block Transmissibility Estimation Using Injection and Production Data in Waterfloods

摘要

Offshore assets instrumentation and monitoring provides a stream of under-utilized dynamic data, yet to be effectively used for reservoir characterization. This paper presents a semi-analytic approach that utilizes injection, production and pressure data to estimate fault-block transmissibility. We incorporate simultaneous pressure and rate history to determine fault status (sealing or leaking), characterize inter-fault block transmissibility, evaluate average reservoir pressure in different reservoir compartments and finally estimate effective flux rate across a leaking fault. Analytical formulation imbedded in the capacitance resistance models (CRM) enabled simultaneous history matching of production and pressure data associated with reservoir compartments communicating through a partially leaking fault. The methodology was implemented in an offshore case study consisting of multiple fault-blocks with active aquifer support and unknown inter-block communications. We used historical injection and production rate data along with sparse average pressure data of each compartment to estimate, flux and transmissibility across the fault, between the reservoirs adjacent to the fault, and also between aquifer and reservoirs. A material balanced based simulation model of an offshore asset was used for validation of the developed technique and sensitivity analysis of the obtained leaking fault transmissibility. This method enabled estimation of effective injection within each fault-block, the amount of aquifer support and the interaction between compartments after simultaneously history matching both rate and pressure of each compartment using CRM.