Production Optimization through Voidage Replacement using Triggers for Production Rate

Abstract

Voidage replacement is a key element in displacement processes, not only for keeping the reservoir pressure at its initial level but also in mitigating surface subsidence in certain fields. Despite its simple definition, it is a complicated process in reservoir management because of uncertainities involved and lack of all required measurements due to economical or technical restrictions. Thus, every single decision parameter and their relative significance in voidage replacement process is important for robust reservoir management. In general, voidage replacement is achieved where injection is based on production. This study investigates the case of triggers where the production rate at the bottom hole conditions is predicated on the bottom hole flowing conditions or reservoir gas injection rate. A full-physics commercial reservoir simulator is coupled with robust optimization software, where a miscible flood operation is modeled with a group bottom hole flowing target coupled with voidage replacement gas and water injection targets. The simulation results of this realistic case is presented in a way to show the relative significance of each operational parameter, which is outlined with tornado charts to serve as a guide in decision making in efficient reservoir management where voidage replacement is a crucial component. It is observed that triggers help to better manage voidage replacement, especially in large reservoirs where reservoir surveillance is a challenge due to number of wells and patterns. The results can be scaled up to different size of reservoirs and patterns with similar recovery processes. This study scrutinizes the feasibility of a reversal of the typical scenario where injection is based on production. Thus, it serves as a useful and realistic example for efficient reservoir management through optimization of voidage replacement through triggers for production rate.

Full‐scale simulation of a nearly depleted gas field in South Africa for carbon utilisation and storage

“…To define different CO 2 EGR scenarios, the concept of voidage replacement was introduced. 53,54 The voidage replacement ratio (VRR) is defined as 55 :…”

“…To define different CO 2 EGR scenarios, the concept of voidage replacement was introduced 53,54 . The voidage replacement ratio (VRR) is defined as 55 : $$\begin{equation} \mathrm{VRR}=\frac{{V}_{\mathrm{inj}}}{{V}_{\mathrm{Prod}}}=\frac{{R}_{\mathrm{inj}}}{{R}_{\mathrm{prod}}} \end{equation}$$where $${V_{{\rm{inj}}}}$$ is the volume of the fluid injected, $${V_{{\rm{Prod}}}}$$ is the volume of the hydrocarbon produced, $${R_{{\rm{inj}}}}$$ is the injection rate and $${R_{{\rm{prod}}}}$$ is the production rate. If the VRR is equal to or greater than 1, the pressure in the reservoir is maintained or increased.…”