Continuous sand production and foamy oil behavior are both believed to be key factors for the enhanced non-

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA fully coupled reservoir-geomechanics model is developed to simulate the enhanced production phenomena both in heavyoil reservoirs (i.e. Northwestern Canada) and conventional oil reservoirs (i.e. North Sea). The model is implemented numerically by fully coupling an extended geomechanics model to a two-phase reservoir flow model. A sand erosion model is postulated after the onset of sand production, which is determined based on the degree of plastic deformation inside the reservoir formation calculated by the coupled reservoir-geomechanics model. Both the enhanced production and the ranges of the enhanced or sanding zone are calculated, the effect of solid production on oil recovery and enhancement are analyzed. Field data for solid production and enhanced oil production from Frog Lake (Lloydminster, Canada) are used to validate the model for the sand rate and sand production.Our studies indicate that the enhanced oil production can be contributed by either (1) the a large-scale reservoir formation mobility improvement, (i.e. wormhole type model), by (2) a higher fluid velocity due to the movement of the sand particles according to the modified Darcy's flow, or by (3) an effective well radius increase or negative skin development due to sand erosion if formation does not permit an extensive erosional zone. Such an improvement on productivity reduces the near well pressure gradient so that the sanding potential is weakened, but permits an easier path for oil to flow into the well due to an enhanced permeability. Two-phase flow can affect pressure gradient and formation residual cohesion due to capillary pressure buildup. Indirectly, production enhancement strategy can be controlled by the water saturation distribution and development, as the success and economic value of a field operation can depend on if sand production can be induced or not. Such an analogy can also be used for a completion strategy by allowing a certain amount of sand production before gravel pack in high flow-rate reservoir.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractHigh viscosity and weak cementation existing in heavy oil reservoirs present great challenge to us in rich heavy oil reservoirs in Northwestern Canada for production and well completion. On one hand, we attempt to increase the exposure of the reservoir to the well so that we can maximize the production potential. On the other, we must select an adequate strategy for well completion in order to maintain the integrity of the well during production. A well completion strategy by cavity-failure mechanism has been used for coalbed methane and heavy oil production during SAGD. The success of their previous operations leads us to investigate the feasibility of such a well completion strategy in both cold production and other enhanced production process in poorly consolidated heavy oil reservoirs. A coupled reservoir-geomechanics model is developed. A black-oil model is fully coupled to a Mohr-Coulomb type elastoplastic geomechanics model. An open hole condition with slotted liner is simulated. The wellbore pressure is rapidly reduced to create a massive dilation zone near the well so that the intact porosity can be mobilized. Consequently, an enhanced zone near the slotted liner with a higher permeability can be generated, leading to negative skin factor during the production. The field conditions reported in Cold Lake are used to evaluate our study and simulations.