Understanding the impact of geology in subsurface reservoir flow processes

Geology plays an important role in the subsurface reservoir flow processes. It is necessary to understand the interaction of geology and multiphase physics in various settings. This work investigates the interaction of multiple types of fluids in different depositional settings. The first study is an investigation of risk analysis of carbon dioxide sequestration in a relatively homogenous sandstone. To properly screen sequestration sites it is necessary to understand how different geologic parameters influence potential risk factors. This is achieved by using a methodology that combines experimental designs with Monte Carlo sampling to develop probability density functions of these critical risk factors. These probability density functions can be used as a first-order screening method during geologic sequestration site selection. The second study involves a full field study to understand the potential for long-term subsurface storage of carbon dioxide given a highly detailed geologic model with limited field production history. An application of best practices for a single well pattern is applied to the northern platform of the SACROC reservoir to determine the ideal conditions for economic return and carbon dioxide sequestration. It is found that either sequestration or oil recovery must be the primary goal with the other becoming secondary. The final investigation involves a unique reservoir type where all fluid flows in faults and fractures rather than the matrix. This investigation attempts to understand the flow dynamics under various geologic and fluid parameter ranges to develop a method for history matching these reservoirs. This is done using a simple model for a parametric study which will assist in understanding the production controls in basement reservoirs. This investigates whether low-rate recoveries will achieve higher overall recoveries due to the flow dynamics in faults and fractures. In no scenario was it possible to recover a higher volume of oil at lower recovery rates unless the geologic parameters are flow rate dependent, which is difficult to justify at this time. In each of these studies the impact of the geological parameters is used to determine either the risk factors or to develop optimal methods for economic recovery of reservoir fluids.