Simulation Of Shale Gas Reservoirs.
Engineering Honours Degree, 2010
University of Adelaide
Production of gas from organically rich shale reservoirs has become an increasingly attractive prospect. The great success of shale gas in the United States over the past decade has driven the search for similar unconventional shale gas reservoirs in Australia.
The shale serves as both the hydrocarbon source rock and the reservoir. Most of the gas is adsorbed on kerogen (organic material) and the rest is stored as free gas in pores and fractures. Because shales have extremely low permeabilities, it is typically regarded as difficult to extract and expensive to produce. However, specialised technological advances have made shale gas wells more economically viable.
This paper presents a simulation study and production forecasting based on typical data for shale gas reservoir. We have used ECLIPSE 300 to model the shale gas production. Critical data such as fluid and reservoir properties and hydraulic fracture characteristics have been incorporated. A two-phase, triple porosity system, shale adsorption-desorption simulation model was used to test multiple scenarios and generate production forecasts. The gas properties were modelled using the PVTi functionality in ECLIPSE.
A sensitivity analysis is performed to quantify the influence of the reservoir and hydraulic fracture parameters including porosity and permeability of the reservoir matrix and fracture, hydraulic fracture half-length, fracture conductivity and initial reservoir pressure. Based on our simulation results, increasing the reservoir pressure and matrix porosity increases the total gas initially in place (GIIP), thus leading to a higher production. However, increasing the fracture porosity lowers the production. Higher fracture and matrix permeabilities improve the gas production rates, resulting in a high recovery factor. Moreover, a longer fracture half-length favours production as area exposed for production increases. Increasing the hydraulic fracture conductivity may not result in a significant difference in the total gas produced although it initially enhances the recovery factor.
All results and recommendations have been discussed and presented in detail. Our study is intended to serve as a preliminary guideline in view of future shale gas development in Australia.