A Semi-Analytical Methodology for Multiwell Productivity Index of Well-Industry-Production-Scheme in Tight Oil Reservoirs

Abstract

Abstract:Recently, the well-industry-production-scheme (WIPS) has attracted more and more attention to improve tight oil recovery. However, multi-well pressure interference (MWPI) induced by well-industry-production-scheme (WIPS) strongly challenges the traditional transient pressure analysis methods, which focus on single multi-fractured horizontal wells (SMFHWs) without MWPI. Therefore, a semi-analytical methodology for multiwell productivity index (MPI) was proposed to study well performance of WIPS scheme in tight reservoir. To facilitate methodology development, the conceptual models of tight formation and WIPS scheme were firstly described. Secondly, seepage models of tight reservoir and hydraulic fractures (HFs) were sequentially established and then dynamically coupled. Numerical simulation was utilized to validate our model. Finally, identification of flow regimes and sensitivity analysis were conducted. Our results showed that there was good agreement between our proposed model and numerical simulation; moreover, our approach also gave promising calculation speed over numerical simulation. Some expected flow regimes were significantly distorted due to WIPS. The slope of type curves which characterize the linear or bi-linear flow regime is bigger than 0.5 or 0.25. The horizontal line which characterize radial flow regime is also bigger 0.5. The smaller the oil rate, the more severely flow regimes were distorted. Well rate mainly determines the distortion of MPI curves, while fracture length, well spacing, fracture spacing mainly determine when the distortion of the MPI curves occurs. The bigger the well rate, the more severely the MPI curves are distorted. While as the well spacing decreases, fracture length increases, fracture spacing increases, occurrence of MWPI become earlier. Stress sensitivity coefficient mainly affects the MPI at the formation pseudo-radial flow stage, almost has no influence on the occurrence of MWPI. This work gains some addictive insights on multi-well performance for WIPS scheme in tight reservoir, which can provide considerable guidance on fracture properties estimation as well as well adjustment of production operation for WIPS scheme.

Effect of Stress-Sensitive Fracture Conductivity on Transient Pressure Behavior for a Multi-Well Pad With Multistage Fractures in a Naturally Fractured Tight Reservoir

“…(1) The pure wellbore storage period regime: It can be identified by a slope of unity on the log-log plots, when DP curve and DPD curve align with each other. This period is mainly dominated by wellbore storage effect (Liu et al, 2018a). (2) The skin effect transition flow regime: The most obvious feature of this stage is a "hump" in the pressure derivative curve.…”

“…(8) The late-time pseudo-radial flow regime: Under the influence of matrix stress sensitivity, the DPD curve does not show a horizontal line, and its value is greater than 0.5. Because of the existence of multi-well pressure interference, the smaller the oil rate is, the greater the distorted value will be (Liu et al, 2018a).…”

“…To reduce operational costs and mitigate the negative environmental impact, multi-well pad schemes have proven to be more effective for exploiting tight oil/gas reservoirs with and without natural fractures (NFs) (Manchanda and Sharma, 2013;Meng et al, 2017;Xiao et al, 2018;Jiang et al, 2020b;Jiang et al, 2020c); however, multi-well pressure interference under multiwell pad schemes severely distorts the flow patterns. In addition to greatly affecting well production, such a distortion inevitably makes the transient pressure analysis more challenging while the stresssensitivity effect and contribution of NFs are usually excluded (Liu et al, 2018a). Therefore, it is of fundamental and practical importance to accurately evaluate performance for a multi-well pad with multistage HFs and NFs in a tight formation by taking their stress-sensitive effects into account.…”

Productivity Models of Infill Complex Structural Wells in Mixed Well Patterns

“…In the semi-analytical model, each branch of the complex structural well is divided into several infinitesimal sections, thus the productivity can be obtained by solving the system of linear equations combined with fluid flow rate and pressure drawdown for each infinitesimal in the wellbore. However, these methods mainly focus on building models of single well or regular well patterns, and little research has been conducted on the seepage theory of mixed well patterns of vertical wells and complex structural wells [24][25][26][27][28][29][30]. In view of the field problems involving the productivity prediction of infill wells in irregular well patterns, there are limitations in current mathematical models [31][32][33][34][35].…”

Multiporosity and Multiscale Flow Characteristics of a Stimulated Reservoir Volume (SRV)-Fractured Horizontal Well in a Tight Oil Reservoir

“…It has been commonly recognized that tight oil reservoirs have threshold pressure gradient and medium deformation characteristics because of their great lithologic compaction, fine pore-throat, and high flow resistance [1][2][3][4][5][6][7]. In recent years, stimulated reservoir volume (SRV) fracturing has become the most efficient technology in tight reservoir formation treatment [8][9][10][11][12][13][14][15].…”