Hydraulic fracturing has become a standard stimulation technology to enhance hydrocarbon production in unconventional reservoirs in recent decades. During organic-rich tight carbonate reservoir stimulation, extensive microfractures will be created and pre-existing microfractures will be opened in the far-field during hydraulic fracturing, but they tend to close after the release of hydraulic pressure due to the larger sizes of the conventional proppants not fitting into the microfractures. The well productivity will be further enhanced if these microfractures can be held open during production, like the primary hydraulic fractures supported by proppants. Based on this idea, industry has introduced microproppants into the pad or pre-pad fluid so that they can be placed into opened microfractures during hydraulic fracturing. In this work, we propose further enhancing the stimulation efficiency by introducing solid delayed acid generating materials (SDAGM)-coated microproppants into the stimulation for the dual function of keeping microfractures open, and, through subsequent reactions of the coating materials with the carbonate formation, creating extra void space inside the microfractures. To prove this concept and help select the appropriate microproppant coating plan, lattice Boltzmann simulation is performed to measure the hydraulic conductivity of the stimulated microfractures under different scenarios that represent corresponding stimulation treatment schemes. The simulations showed that fracture conductivity of the microfractures can be significantly improved by placing SDAGM-coated microproppant into them. Using the mixed uncoated and SDAGM-coated microproppants (Scheme II) may have better fracture conductivity improvement than using the coated microproppant alone (Scheme I).

中文翻译：

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采用格子玻尔兹曼法评价 SDAGM 包覆微支撑剂在水力压裂中的性能

近几十年来，水力压裂已成为提高非常规油藏油气产量的标准增产技术。富有机质致密碳酸盐岩储层改造过程中会产生大面积微裂缝，水力压裂过程中会在远场打开预先存在的微裂缝，但由于常规裂缝尺寸较大，在释放水力压力后往往会闭合。支撑剂不适合微裂缝。如果这些微裂缝可以在生产过程中保持开放，例如由支撑剂支撑的主要水力裂缝，井的产能将进一步提高。基于这个想法，工业界已将微支撑剂引入垫层或预垫层流体中，以便在水力压裂过程中将它们置于打开的微裂缝中。在这项工作中，我们建议通过将固体延迟酸生成材料 (SDAGM) 包覆的微支撑剂引入增产措施，以进一步提高增产效率，以实现保持微裂缝开放的双重功能，并通过涂层材料与碳酸盐形成的后续反应，创造额外的空隙空间微裂缝内。为了证明这一概念并帮助选择合适的微支撑剂涂层方案，进行格子玻尔兹曼模拟以测量在代表相应增产处理方案的不同情景下增产微裂缝的导水率。模拟表明，通过将 SDAGM 包覆的微支撑剂放入其中，可以显着提高微裂缝的裂缝导流能力。