考虑多重应力敏感效应的页岩气藏压裂水平井试井模型

doi:10.7657/XJPG20210614

摘要/Abstract

摘要：

页岩气藏存在多尺度孔隙结构,流体运移方式多样,包括吸附、扩散和非达西渗流。目前页岩气多重运移流动模型仅考虑天然裂缝的渗透率和孔隙度为应力敏感系数,但实验表明扩散系数也具有应力敏感性。建立考虑多重应力敏感效应的压裂水平井试井分析模型,能准确分析和预测页岩储集层和流体参数,对页岩气藏生产动态分析和开发方案编制十分必要。基于页岩储集层多尺度孔隙结构,假设页岩气藏具有基质和裂缝系统的双重介质,考虑流体多重流动机理,建立以扩散系数、天然裂缝渗透率和孔隙度为应力敏感系数的压裂水平井试井分析模型,分析了压裂规模和页岩储集层特征参数对试井曲线的影响。结果表明,压裂规模参数主要影响气藏开采早期,页岩储集层特征参数主要影响气藏开采晚期。针对中国典型页岩气区进行分析,提出的试井分析方法能较好地拟合生产数据,可为页岩气藏高效开发提供一定借鉴。

关键词: 页岩气藏, 压裂水平井, 应力敏感效应, 多重流动机理, 试井分析, 孔隙结构, 双重介质, 历史拟合

Abstract:

Shale gas reservoir has multi-scale pore structures, so that shale gas flows in multiple ways including absorbing, diffusing and non-Darcy flow. Present shale gas flowing models only take the permeability and porosity of natural fractures as stress sensitivity factors, but experiments show that the diffusion coefficient is also sensitive to stress. To accurately predict and analyze shale gas reservoir and fluid parameters, it is necessary to establish a fractured horizontal well test model which should consider multi-scale pore structures and multiple gas flowing mechanisms, and it is also helpful to production performance analysis and subsequent development plan making. In this study, according to the multi-scale pore structures, and assuming that the shale gas reservoir is a dual medium with matrix and fractures, we built a fractured horizontal well test model which takes diffusion coefficient, and porosity and permeability of natural fractures as stress sensitive parameters, and analyzed the effects of fracturing scale and reservoir parameters on well test curve. The results show that fracturing parameters mainly affect early post-fracturing production, while reservoir parameters mainly affect late production. The model was applied in a typical shale reservoir block in China, and the modelling result well matched with the measured production data. It is a guiding reference to effective development of shale gas reservoirs.

Key words: shale gas reservoir, fractured horizontal well, stress sensitive effect, multiple flow mechanism, well test analysis, pore structure, dual medium, history matching

中图分类号:

TE37

卢婷, 王鸣川, 马文礼, 彭泽阳, 田玲钰, 李王鹏. 考虑多重应力敏感效应的页岩气藏压裂水平井试井模型[J]. 新疆石油地质, 2021, 42(6): 741-748.

LU Ting, WANG Mingchuan, MA Wenli, PENG Zeyang, TIAN Lingyu, LI Wangpeng. Fractured Horizontal Well Test Model for Shale Gas Reservoirs With Considering Multiple Stress Sensitive Factors[J]. Xinjiang Petroleum Geology, 2021, 42(6): 741-748.

图/表 7

图1

图2

表1

页岩气藏试井数学模型中相关参数的表达式"

参数	表达式
无因次拟压力	$ψ D = π k fi h T sc p sc q sc T Δ ψ$ , $Δ ψ = ψ i - ψ$	（1）式,（2）式
无因次产量	$q D = q sc p sc T π K fi h T sc Δ ψ$	（3）式
无因次径向半径	$r D = r L ref$	（4）式
无因次控制半径	$r eD = r e L ref$	（5）式
无因次吸附气体积分数差	$V D = V i - V$	（6）式
无因次时间	$t D = K fi t μ gi ϕ C gi + 2 π K fi h q sc μ gi 1 - ϕ L ref 2$	（7）式
无因次基质孔隙半径	$r mD = r m r n$	（8）式
无因次渗透率应力敏感系数	$γ D = μ g Zγ p sc q sc T 2 p f π K fi h T sc$	（9）式
无因次裂缝线源产量	$q ˜ fD = q ˜ f q sc$	（10）式
第i段第j节无因次产量	$q D ij = q ij L ref q sc$	（11）式
第i段第j节裂缝无因次长度	$∆ L fD ij = ∆ L f ij L ref$	（12）式
储容比	$ω = ϕ C gi ϕ C gi + 2 π K fi h q sc μ gi 1 - ϕ$	（13）式
窜流系数	$λ = μ gi ϕ C gi + 2 π K fi h q sc μ gi 1 - ϕ L ref 2 D K fi r n 2$	（14）式
吸附系数	$σ = p sc q sc T π kh T sc ψ L V L ψ L + ψ i 2$	（15）式

表1

图3

图4

图5

图6

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