The Use of Localized Well-Drainage Reservoir Pressure Model in Optimum Fracture Design

This study is to determine the effective use of localized reservoir pressure of each well drainage area in a multi-well reservoir system model to determine optimum fracturing design for production improvement. A static bottom-hole pressure (BHP) survey may present different values for each well draining from the same reservoir but these different pressure values have not been incorporated into determining the performance of each individual well based on the pressure as seen by each well, rather an indeterminate average reservoir pressure is used. Fracturing as a concept of increasing reservoir permeability will further expose the well to reservoir pressure as seen by the individual well than the assumed single-value reservoir-wide pressure. This is so except when the fracture half-length is equal to the drainage length of the reservoir, connecting the whole reservoir to justify the single reservoir pressure effect if it is a single-well reservoir system. In reality, many reservoirs are multi-well reservoir systems and this simplified assumption may pose some drawbacks. The damaged wellbore area may truly be more exposed to the localized reservoir pressure as seen by the well than the apparent reservoir single value pressure assumed to determine drawdown and damage. In a multi-well reservoir system with each well-drainage area subjected to different reservoir pressures than the single reservoir pressure, fracturing and stimulation candidates screening may not present the actual effect of each well-drainage area static reservoir pressure. This paper is to present a new model that incorporates the average reservoir pressure for whole reservoir system and the reservoir pressure as seen by individual wells in the determination of the drawdown and damage. The knowledge of the different pressures in different well locations in the reservoir system will be utilized to present a linear flow model in well fracturing to enhance better well performance. With this new model, the actual and more realistic damage estimation and ways to achieve a linear flow for optimum performance through fracturing will be better understood. The effect of other flowing wells on the skin of the candidate well will enhance a better planning than is done now because the existing formulations are done with a single-well reservoir system in mind; no account for contributing skin of other flowing wells in the industry applied model approaches.