朱维耀, 张启涛, 岳明, 张燎源. 裂缝网络支撑剂非均匀分布对开采动态规律的影响[J]. 工程科学学报, 2020, 42(10): 1318-1324. DOI: 10.13374/j.issn2095-9389.2019.10.23.001
引用本文: 朱维耀, 张启涛, 岳明, 张燎源. 裂缝网络支撑剂非均匀分布对开采动态规律的影响[J]. 工程科学学报, 2020, 42(10): 1318-1324. DOI: 10.13374/j.issn2095-9389.2019.10.23.001
ZHU Wei-yao, ZHANG Qi-tao, YUE Ming, ZHANG Liao-yuan. Effect of uneven distribution of proppant in fracture network on exploitation dynamic characteristics[J]. Chinese Journal of Engineering, 2020, 42(10): 1318-1324. DOI: 10.13374/j.issn2095-9389.2019.10.23.001
Citation: ZHU Wei-yao, ZHANG Qi-tao, YUE Ming, ZHANG Liao-yuan. Effect of uneven distribution of proppant in fracture network on exploitation dynamic characteristics[J]. Chinese Journal of Engineering, 2020, 42(10): 1318-1324. DOI: 10.13374/j.issn2095-9389.2019.10.23.001

裂缝网络支撑剂非均匀分布对开采动态规律的影响

Effect of uneven distribution of proppant in fracture network on exploitation dynamic characteristics

  • 摘要: 水力压裂过程中支撑剂的注入是为了防止地应力将已压裂出的裂缝重新闭合。为了研究复杂裂缝网络中支撑剂的运移分布规律,及支撑剂非均匀分布对开采动态规律的影响,基于作者之前提出的数个数学模型,建立了致密储层压裂注砂开发耦合计算模型。通过计算结果可以得知:裂缝网络中,支撑剂会在裂缝交汇处大量堆积,砂堤高度高于缝网其他部分。次级裂缝中的支撑剂更多的处于悬浮状态,且支撑剂沉降堆积高度相较于主裂缝小25%~50%,相互沟通的次级缝具有更高的支撑剂沉降程度。缝网中支撑剂非均匀分布对模拟计算结果具有较大影响,当储层渗透率为0.05 mD时,忽略支撑剂非均匀分布计算出的产量高出实际值41.7%,因此在进行低渗透率储层模拟时,支撑剂非均匀分布状态不可忽略;当基质渗透率为5 mD时,产量计算差异在5%以内,此时不考虑支撑剂非均匀分布相对合理。

     

    Abstract: Proppant injection during hydraulic fracturing is to prevent the closure of hydraulic fractures. As a result, the distribution of proppant in the fracture impact the productivity to a great extent. In order to study the rule of proppant transportation and distribution in complex fracture network, and the influence of uneven proppant distribution on the exploitation dynamic characteristics, a full-coupled 3D finite element method calculation model for tight oil reservoir considering sand injection during hydraulic fracturing was established, based on several mathematical models proposed by the author in the past. In the model, a mixture model was utilized, which had advantages to deal with two-phase flow containing solid particles in dispersed phase, to simulate the proppant transportation process in fracture networks. Then, a tight oil reservoir model was established to evaluate the effect of the proppant distribution on the reservoir performance. The calculation results show that in the fracture network, proppant particles will accumulate at the fracture intersection, and the proppant concentration is higher than other parts of the fracture network. The height of proppant settlement dune in the secondary fracture is 25%–50% lower than that in the main fracture, and the communication of secondary fractures has enhanced the proppant settlement degree. Moreover, factors like injection velocity, proppant materials and proppant size are proved to have a strong relation to the average conductivity of fracture network, which could impact the fracture design considerably. Furthermore, the uneven distribution of proppant in fracture network has a great influence on the simulation results. When the reservoir permeability reaches 0.05 mD, the calculation results show that the height, without considering the uneven distribution, of proppant settlement is 41.7% higher than the actual value. Therefore, the uneven distribution of proppant cannot be ignored in the simulation of low permeability reservoir. However, when the matrix permeability is 5 mD, the difference between the actual and simulated result will be within 5%. Thus, it is reasonable to neglect the uneven distribution of proppant in estimations.

     

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