Transient Flow of a Horizontal Well with Multiple Fracture Wings in Coalbed Methane Reservoirs

Abstract

Horizontal wells with multi-stage fractures have been widely used to improve coalbed methane (CBM) production from coalbed methane reservoirs. The main focus of this work is to establish a new semi-analytical method in the Laplace domain and investigate the transient pressure behavior in coalbed methane reservoirs. With the new semi-analytical method, flow regimes of a multi-fractured horizontal well in coalbed methane reservoirs were identified. In addition, the sensitivities of fracture conductivity, diffusion model, storability ratio, inter-porosity flow coefficient, adsorption index, fracture spacing, fracture asymmetry, non-planar angle, and wellbore storage were studied. Results indicate that six characteristic flow regimes can be identified for multi-fractured horizontal wells in coalbed methane reservoirs, which are bilinear flow, first linear flow, desorption-diffusion flow, first pseudo-radial flow, second linear flow, and second pseudo-radial flow. Furthermore, the sensitivity analysis shows that the early flow is mainly determined by the fracture conductivity, the asymmetry factor, the non-planar angle, and the wellbore storage; while the desorption-diffusion flow regime is mainly influenced by the diffusion model, the storability ratio, the inter-porosity flow coefficient, the adsorption index, and the fracture spacing. Our work can provide a deep insight into the fluid flow mechanism of multi-fractured horizontal wells in coalbed methane reservoirs.

Quasi-Analytical Model of the Transient Behavior Pressure in an Oil Reservoir Made Up of Three Porous Media Considering the Fractional Time Derivative

“…To obtain the associated constants D 1 , D 2 , D 3 , note that, when replacing the solutions obtained, the Equations (48)-(50) in the boundary conditions, Equations (25) and (26), the following matrix system is reached…”

“…On the other hand, Tian et al [25] investigated the transient pressure behavior in a horizontal well in coalbed methane reservoirs with multiple fracture wings by identifying the characteristic flow periods. Meanwhile, Gao et al [26] addressed the problem of fast pressure drop and gas well abandonment caused by well interference; divided the region around the MFHW into three regions and solved the model using finite volumes and concluded that the IWCM can effectively control the resources within the reservoir around the well.…”

Flowing Material Balance and Rate-Transient Analysis of Horizontal Wells in Under-Saturated Coal Seam Gas Reservoirs: A Case Study from the Qinshui Basin, China

“…The RTA of a multi-staged hydraulically fractured horizontal well is complicated and may require additional information, such as a micro-seismic interpretation, to obtain promising results [1,2,12,13]. The production history (recorded on a daily basis) of a typical horizontal well may exhibit five flow regimes, namely, early radial, formation linear, elliptical, pseudo-radial, and boundary-dominated flow regimes [1].…”

Production Analysis for Fractured Vertical Well in Coal Seam Reservoirs with Stimulated Reservoir Volume

“…The influence of coal seam pressure difference on single well production is demonstrated. Tian et al [23] studied the flow characteristics of horizontal well with multiple fracture wings. The semianalytical solution model of horizontal well with multiple fracture wings is established, and the flow stage of the model is defined.…”