Performance Of Vertically Fractured Wells With Finite Conductivity Fractures

Author : Liwu Jiang
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

DOWNLOAD NOW!

Download or read book Performance Evaluation of Horizontal Wells With Multistage Fractures in Tight Formations by Considering Non-Darcy Effect and Fracture Dynamics written by Liwu Jiang and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance evaluation of fractured wells has attracted increasing attentions since horizontal drilling and hydraulic fracturing technologies have been successfully and efficiently applied in tight formations; however, such an evaluation process is physically complex and mathematically challenging due to the composite effects of non-Darcy flow within fractures and fracture dynamics including complex fracture geometry, fracture network, and stress-sensitive permeability. It is of fundamental and practical importance to evaluate the production performance of a fractured well by taking the aforementioned composite effects into account in a consistent and accurate manner. A new slab source function was developed in the Laplace domain for improving the prediction accuracy on the early time transient pressure response which can take the fracture width into account. The semi-analytical method was used to solve the fluid flow problem through such hydraulic fractures each of which is discretized into small segments, while continuity equations at the interface of such discretized fracture segments were applied to generate the coupled matrix-fracture flow model. The effect of complex fracture geometry and shape-dependent conductivity on the transient pressure response are then examined and discussed. The fracture width is found to affect the early time transient pressure response, while the shape-dependent conductivity imposes a key impact on the transient pressure behaviour for the early and intermediate periods. A coupled matrix-fracture flow model is then proposed and solved in the Laplace domain with consideration of the aforementioned composite effects which may escalate the nonlinearity of the governing equations. An iterative method was developed to deal with the nonlinearity caused by non-Darcy flow in fractures, while the Pedrosa's transform formulation and perturbation technique is used to weaken and linearize the nonlinear effect caused by stress-sensitive permeability. It is found that the non-Darcy effect dominates the early time flow regime, while stress-sensitive effects in fractures and matrix mainly affect the transient pressure response for the intermediate- and late-stage flow regimes. The Laplace-transform difference method was further adopted to extend the current simplified fracture models more closely to reality by taking complex fracture networks into account. The fracture network is first discretized into small segments, and the finite difference method in the Laplace domain can be used to solve the fluid flow problem through such complex fracture systems. Furthermore, the effect of fractal-like discrete fracture network on the transient pressure behaviour can be examined, while the combined effects of complex fracture networks and stress-sensitive permeability can then be analyzed. Transition flow regime is identified for the scenarios with discrete natural fracture networks which can be affected by the stress-sensitive permeability in natural fractures. All the theoretical models have been validated and then extended to field cases. Type curves are generated and beneficial to examine the effect of each factor on the transient behaviour for horizontal wells with multistage fractures in tight formations under various conditions. The discrepancy between the real field pressure data and the traditional type curves without non-Darcy and stress-sensitive effects can be used to evaluate the degree of these two effects. Two new flow regimes including the fluid feed and transition flow regimes occurred in real field pressure tests can be employed to quantify the complexity of the hydraulic and natural fracture networks, respectively.