A study of produced water disposal into aquifer by black oil reservoir simulator

Abstract

Produced water (PW) is one of the byproducts from gas and gas-condensate production in many gas fields in the Gulf of Thailand. One method to dispose the PW is to inject into shallow aquifer through injection wells. The advantages of this method are high disposal capacity, potential harmful fluids are permanently removed from direct human and indirect food chain, interaction and to prevent generation of byproducts from the treatment process. In this study, the most suitable formations sand units A and B in M field in the Gulf of Thailand was selected. The reasons are high porosity, permeability and reservoir volume. Two wells were used to inject the PW into shallow aquifers, located above the producing formation. In this study, a 3D reservoir simulator ECLIPSE 100 is used to perform reservoir model construction and performance prediction. The reservoir simulation models of targeted sand units were constructed based on structural map, well logging data and special core analysis data. Initial reservoir conditions and fluid properties were input to complete the models. After initializing the homogeneous model (HM), Channel-I and Channel-II models were generated to introduce heterogeneity. Under the three models a number of simulation cases were run at different initial well injection rates with single and both well injection options in order to investigate injection capacity and performance. The impact of different well injection rates on injection capacity and performances were investigated. In addition, under intermittent injection the gain of injection performance (IP) was also investigated. Finally, the best sand candidate in terms of maximum cumulative injection volume was recommended.