Multivariate Fracture Treatment Optimization for Enhanced Gas Production From Tight Reservoirs

An integrated model for multivariate fracture treatment optimization with adequate trade-offs between production enhancement, equipment capacity, and formation compatibility requirements was presented. The model considered both fracture geometry (length, height, width, etc.) as well as treatment parameters as free design variables. Compatibility relationships between reservoir properties, treatment parameters and fracture growth were formulated using a modified pseudo-three-dimensional fracture model. The optimal design of fracturing treatments to maximize cumulative production was also presented by as series of applications of the model to a tight-gas reservoir. The model was run with three different initial designs (points) shown at zero iteration. All three initial designs converged to a significantly improved optimum design within a few iterations, which were though continued further to achieve an absolute three-level convergence. Initial Design 1 was improved by 13%, Initial Design 2 by 33%, and Initial Design 3 by 64%. Thus, the model greatly enhanced the capability of a designer to achieve the best possible treatment design starting with any initial design. The proppant concentration directly increased the fracture conductivity, and in turn the production return, which exceeded the increase in proppant cost. Using the optimization model, sensitivities of various treatment parameters were studied in production maximizations.