Optimal Strategy of Disposing of Mercury-Contaminated Waste

摘要

Mercury contaminated waste is one of the byproducts fromrnhydrocarbon production in many gas fields in the Gulf ofrnThailand. One method to dispose the toxic waste is to injectrnmercury contaminated waste into confined depleted reservoirsrnthrough a depleted well. The advantages of this approach arernhigh disposal capacity and permanent waste elimination. In thernselected field of this study, the most suitable structure which isrnconfined and in the last stage of production, was chosen. Sincernthe selected reservoirs are not completely depleted, gas shouldrnfirst be produced. Thus, there is a need to optimize both thernproduction and waste disposal strategy. In this study, a 3Drnreservoir simulator is used to determine strategy, whichrnmaximizes gas production and mercury contaminated wasterndisposal.rnThe reservoir simulation model for the reservoirs in thernchosen compartment was constructed from seismic, well log,rnand special core analysis data. Initial reservoir conditions andrnfluid properties were entered into the model, and historyrnmatching on production performance and reservoir pressurernwas performed to fine tune the reservoir model. Then,rnreservoir simulation was performed to optimize hydrocarbonrnproduction by varying perforation plan and production gasrnrate. Finally, mercury contaminated slurry injection wasrnoptimized by performing sensitivity simulation on slurryrndensity, injection rate, and slurry viscosity. The effect of thesernparameters on injection capability was also investigated. Thernoptimal injection criterion is minimum injection time under arncondition that the injection pressure is not high enough torncreate any fracture in the reservoirs.