(163e) 3D Heterogeneous Reservoir Modeling Forecasts of Gas Production By Depressurization of the Prudhoe Bay Unit “L Pad” Hydrate Deposits

The emerging possibilities with the exploration of gas hydrates as an unconventional source of energy have spurred many objectives for research studies going on in this area. One of these is the U.S national hydrate research program whose primary goal is to determine the recoverability and commercial viability of gas production from hydrate reservoirs. So far, many research efforts to determine nature of hydrate dissociation in a hydrated reservoir have included both field tests and laboratory experiments, which are very expensive in terms of time and capital. More recently, researchers have been investigating production of natural gas from hydrate reservoirs by developing simplistic reservoir flow models, which are less expensive compared to field tests and laboratory experiments. However, as with models of any kind, the main drawback with reservoir models is that they may not be true representative of physical reality.

As a result, this work seeks to provide an advanced evaluation of the gas production potential of hydrate reservoirs by developing robust hydrate reservoir models which incorporate extensive field data. The main goal of this work is to provide support to a proposed short-term field production test to be carried out on the Alaska North Slope (ANS), with the hydrate deposits within the region of Prudhoe Bay Unit (PBU) being the primary subject of investigation.

Geostatistical analysis is used to obtain stochastic simulations of the 3D distribution of reservoir properties (such as porosity and hydrate saturation) in the target hydrate-bearing sand. CMG STARS, a numerical solver, is used to solve the material and energy balance equations in which an equilibrium model of hydrate dissociation was used. An assessment of the extent of hydrate reservoir disturbance due to depressurization is carried out under varying field test scenarios. Predicted gas and water production rates and the design and operational factors that would affect production are the key results of interest.