A semianalytical approach to estimate fracture closure and formation damage of vertically fractured wells in tight gas reservoir

This paper presents a new semianalytical method to estimate the fracture closure and formation damage by formation evaluation in tight gas reservoirs. A new well interpretation model is established by assuming that the fracture half-length can be divided into N segments with different fracture conductivity and flux density. New semi-analytical solutions and type curves are developed based on this model, while sensitivity analysis is also conducted. The pressure and pressure derivative behavior show that the multi-segment fracture model exists new flow regimes which are termed first interference formation linear flow and second interference formation linear flow and can be characterized by straight line with slope m1 and m2 on the pseudo bottom-hole pressure derivative curve. The case study in field tests highlights the accuracy of this new model in the interpretation of formation and fracture characteristics compared with conventional uniform-flux fracture model, especially the effective fracture half-length. The extent of fracture closure and formation damage evaluated by this new method can be further applied to enhance tight gas recovery.