Well and reservoir managemaent for mercury contaminated waste disposal

Abstract

Mercury contaminated waste is one of the byproducts from hydrocarbon production in many gas fields in the Gulf of Thailand. One method to dispose the waste is to inject mercury contaminated waste into confined depleted reservoirs through a depleted well. The advantages of this approach are high disposal capacity and permanent waste elimination. In the field selected for this study, the most suitable structure called the MN compartment, which is a confined and in the last stage of production, was chosen. Since the selected reservoirs are not completely depleted, gas should first be produced. Thus, there is a need to optimize both the production and waste disposal strategy. In this study, a 3D reservoir simulator is used to maximize gas production and Hg contaminated waste disposal. The reservoir simulation model for the reservoirs in the MN compartment was constructed from seismic, well logging, and special core analysis data. Initial reservoir conditions and fluid properties were entered into the model, and history matching on production performance and reservoir pressure was performed to fine tune the reservoir model. After that, reservoir simulation was performed to optimize hydrocarbon production by varying perforation plan and wellhead production pressure. Finally, mercury contaminated slurry injection was optimized by performing sensitivity simulation on slurry density, injection rate, and slurry viscosity. The effect of these parameters on injection capability was also investigated. The optimal injection criterion is minimum injection time under a condition that the injection pressure is not high enough to create any fracture in the reservoirs