Design Optimization Of Horizontal And Vertical Well Patterns In Low Permeability Reservoirs

Basing on the study of developing low permeability reservoir with the application of horizontal wells in domestic and abroad, synthetical analyses the advantage using horizontal wells and the questions of horizontal wells pattern disposition in the low permeability reservoir now, the thesis designs optimization a kind of method of horizontal wells patterns disposition with low permeability reservoir by using of reservoir engineering, numerical simulation, economic evaluation, including the optimization of well spacing density, well pattern and the combinations of well pattern.At first, in this paper solutions of productivity formulas for common reservoirs are directly developed using equivalent flow resistance method, secondly aimed to the characteristics of the reservoir with low permeability, new physical models of wells pattern and their production formulas are presented in the exist of the start-up pressure gradient, then curves of critical well spacing dominated by the start-up pressure gradient are figured based on related calculations, and finally gets the technological limit well spacing density. Based on the difference of wells type, the optimization model of well spacing density with low permeability is obtained using the macroscopic empirical formula, not only considering the effect of water injection rate on water injection sweep efficiency and recovery, but the economic benefit about accompanying gas. Based on the technology limit pattern size restraint, establishes the rational pattern size in the optimized model of low permeability oil reservoir.About the optimization of well patterns and the combinations of well pattern, the method designs different combinations of well pattern and reservoir parameters (fracture), with concludes the appropriate-matching of injection-production well patterns of vertical wells and horizontal wells, well array direction and fracture direction, flooding well spacing and horizontal wells length. Through different combinations, analyzes the predicted production velocity, cumulative production, water content, and reservoir percent, then gets the optimal matching of well array direction, pattern of spacing and density in low permeability.