Wellbore stability in naturally fractured formations featuring dual-porosity/single-permeability and finite radial fluid discharge
Wellbore stability in naturally fractured formations featuring dual-porosity/single-permeability and finite radial fluid discharge
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DOI：
10.1016/j.petrol.2018.11.088
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发表时间：
2019-03
影响因子：
--
通讯作者：
Meng Meng-Meng;Silvio Baldino;S. Miska;N. Takach
中科院分区：
文献类型：
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作者：
Meng Meng-Meng;Silvio Baldino;S. Miska;N. Takach
这项工作提出了一个分析解决方案，倾斜的井眼钻在裂缝性地层显示在裂缝和多孔基质中的扩散速率之间的高对比度，后者被视为存储相，从而不参与流体输送。这种情况可能由不同的泥饼形成速率和/或岩石基质相对于所使用的钻井液的不利润湿性引起。与文献中可用的模型不同，裂缝的特征在于更现实的有限径向流体排放（即，水力连接到井筒的裂缝网络具有有限的范围）。该模型的输出方面的孔隙压力，总应力和有效应力响应已被广泛接受的双孔隙度/双渗透率模型的结果进行了比较。主要差异和渐近行为进行了分析。随后，该模型的结果已被用于执行全面的井筒稳定性分析。研究了时间依赖性、裂缝网络长度和岩石性质对井眼不稳定性的影响，并使用几种破坏标准确定了泥浆重量的上限和下限。研究表明，在双孔单渗条件下，该模型能提供理论上更为保守的泥浆比重预测值。
This work presents an analytical solution for an inclined wellbore drilled in a fractured formation displaying a high contrast between the diffusion rates in the fractures and in the porous matrix, with the latter treated as a storage phase and thus not participating in the fluid transport. This scenario may result from different mud cake building rates, and/or adverse wettability of the rock matrix with respect to the drilling fluid being used. Different from the models available in the literature, the fractures are characterized by a more realistic finite radial fluid discharge (namely, the fractures network hydraulically connected to the wellbore is of limited extent). The model's output in terms of pore pressures, total stresses and effective stresses response has been compared with the results of a widely accepted dual-porosity/dual-permeability model. Major differences and asymptotic behaviors have been analyzed. Subsequently, the results of the model have been used to perform a comprehensive wellbore stability analysis. The effect of time dependency, fractures network length and rock properties on the instability of the borehole have been investigated, and upper and lower mud weight bounds have been determined using several failure criteria. This investigation shows that under the specified conditions where dual-porosity/single-permeability conditions arise, the proposed model provides with theoretically more conservative mud weights predictions.