低渗油藏不规则缝网压裂水平井产能预测模型

doi:10.19596/j.cnki.1001-246x.8745

摘要/Abstract

摘要：

考虑压裂形成的非均匀复杂裂缝网络，引入分形理论并结合裂缝系统应力敏感特征刻画流体渗流能力，建立了低渗油藏压裂水平井三区耦合渗流产能预测模型。采用拉普拉斯变换、摄动理论和数值反演的方法求得产能模型解析解，并推导水平井均匀布缝和非均匀布缝两种情况下单井产能公式。基于海上油田某压裂水平井基本参数和真实生产数据验证了所建产能预测模型的可靠性，并对水平井产能影响因素进行分析。研究结果表明：应力敏感系数和启动压力梯度越小，产油量越大；分形维数越大，水平井产量越大；产油量随裂缝数量和裂缝半长的增大而增大，但增长幅度减缓，参数存在最优值。

关键词: 低渗油藏, 压裂水平井, 裂缝网络, 分形, 产能预测

Abstract:

A non-uniform complex fracture network structure formed by fracturing is considered with introducing the fractal theory and combining the stress sensitivity of fracture system to demonstrate the change of fluid flow capacity, and a production prediction model for three-zone compound seepage flow in fractured horizontal wells in low permeability reservoirs is established successfully in this paper. Laplace transform, perturbation theory, and numerical inversion are applied to obtain the analytical solution of the proposed production model, and the productivity formulas for single well under two situations of uniform and non-uniform distribution of fractures in horizontal wells are derived. The reliability of the production prediction model is verified with the real production data and basic parameters of a fractured horizontal well in Bohai oilfield, and the effects of related influential parameters on production of horizontal well are analyzed. The research results show that smaller the stress sensitivity coefficient and threshold pressure gradient results in larger the oil production. Larger the fractal dimension contributes to larger the horizontal well production. Additionally, the oil production increases with the increase of the number of fractures and fracture half-length, but the growth rate slows down, which means these parameters have optimal values.

Key words: low permeability reservoirs, fractured horizontal wells, fracture network, fractal, production prediction

中图分类号:

O469

刘思雨, 王坤, 谢明英, 冯沙沙, 李黎, 高阳. 低渗油藏不规则缝网压裂水平井产能预测模型[J]. 计算物理, 2024, 41(4): 503-514.

Siyu LIU, Kun WANG, Mingying XIE, Shasha FENG, Li LI, Yang GAO. A Production Prediction Model for Fractured Horizontal Wells with Irregular Fracture Network in Low Permeability Reservoirs[J]. Chinese Journal of Computational Physics, 2024, 41(4): 503-514.

图/表 10

图1 低渗油藏压裂水平井三区耦合渗流物理模型

Fig.1 Three-zone composite seepage model for fractured horizontal wells in low permeability reservoir

图2 压裂水平井裂缝的均匀分布

Fig.2 Uniform fracture distribution of fractured horizontal wells

图3 压裂水平井裂缝的非均匀分布

Fig.3 Non-uniform fracture distribution of fractured horizontal wells

表1 海上油田某压裂水平井基本参数

Table 1 Basic parameters of a fractured horizontal well in Bohai Oilfield

参数	取值	参数	取值
油藏初始压力，p₀/MPa	56	地层原油黏度，μ₁, μ₂, μ₃/(mPa·s)	1.13
井底流压，p_w/MPa	43	主裂缝初始渗透率，k₁₀/D	25
储层形状因子，α/(10³ m^-2)	1.5	裂缝网络初始渗透率，k₁₀/mD	450
主裂缝宽度，w_f/(10² m)	1	基质渗透率，k_2m, k₃/mD	7.4
油藏半宽，x_e/m	200	储层有效厚度，h/m	32
基质系统孔隙度，Ø_2m, Ø₃/%	13.7	原油体积系数，B	1.361
裂缝系统孔隙度，Ø₁, Ø_2f0/%	15	分形维数，D	1.532
裂缝数量，N_f/条	5	裂缝间距半长，y_e/m	40
应力敏感系数，γ/MPa^-1	0.095	启动压力梯度，G₃/(MPa·m^-1)	0.001 2

图4 模型结果与实际日产

Fig.4 Model results vs. real production data

图5 裂缝半长对水平井产量的影响 (a)日产量；(b)累计产量

Fig.5 Effect of fracture half-length on production of horizontal wells (a) daily production rate; (b) cumulative production rate

图6 裂缝数量对水平井产量的影响 (a)日产量；(b)累计产量

Fig.6 Effect of fracture number on production of horizontal wells (a) daily production rate; (b) cumulative production rate

图7 分形维数对水平井产量的影响 (a)日产量；(b)累计产量

Fig.7 Effect of fractal dimension on production of horizontal wells (a) daily production rate; (b) cumulative production rate

图8 应力敏感系数对水平井产量的影响 (a)日产量；(b)累计产量

Fig.8 Effect of stress sensitivity factor on production of horizontal wells (a) daily production rate; (b) cumulative production rate

图9 启动压力梯度对水平井产量的影响 (a)日产量；(b)累计产量

Fig.9 Effect of threshold pressure gradient on production of horizontal wells (a) daily production rate; (b) cumulative production rate

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