考虑支撑剂及其嵌入程度对支撑裂缝导流能力影响的数值模拟

Numerical simulation considering the impact of proppant and its embedment degree on fracture flow conductivity

目前支撑剂粒径、铺置浓度、嵌入程度对裂缝导流能力的影响主要为实验研究,缺乏相应的理论计算模型研究,而理论计算模型会促使压裂方案设计更加合理、可靠,增加施工的成功率,达到预期的改造效果。为此,根据Carman-Kozeny公式,建立了一种考虑支撑剂在岩石表面嵌入的支撑裂缝导流能力数值计算模型,利用实验数据对理论模型进行拟合校正,并通过校正后的理论模型计算了20～40目、30～50目和40～70目支撑剂在不同铺置层数、不同嵌入程度条件下的裂缝导流能力,分析了铺置层数、嵌入程度对导流能力的影响。结果表明:支撑剂粒径越大、铺置层数越多,裂缝导流能力越大;在单层铺置情况下,嵌入程度对导流能力的影响较大,嵌入程度从0增加到33%,导流能力降低85%。所建立的模型为致密油、页岩气等不同类型储层的粒径优选、砂比优化提供了参考和依据,也为后续考虑支撑剂嵌入的相关软件研究提供了理论模型。

The present experimental studies always focus on the impact of proppant particle size, proppant concentration and embedment degree on the fracture flow conductivity, while few studies on the corresponding theoretical calculation model, which, however, can make the fracture project design more reasonable and reliable to improve the success rate of the construction and achieve the expected reservoir stimulation effect. To this end, a numerical calculation model was established considering the flow conductivity of the propped fracture embedded by the proppant on the rock surface according to the Carman Kozeny Formula. Fitting correction was also conducted for this theoretical model based on experimental data, and then the model was used to calculate the fracture flow con- ductivity respectively of 20 - 40 meshes, 30 - 50 meshes and 40 - 70 meshes proppant under different paved layers and embedment de- grees, the influence of which were also discussed. The results show that the larger the proppant particle size and the more paved lay- ers, the higher the flow conductivity. As for the single paved layer, when the embedment degree increased from 0 to 33 ~, the flow conductivity decreased by 85%. The established model provides a reference to and a basis for particle size selection and sand ratio op timization of multiple reservoirs including tight oil and shale gas. It is also a theoretical model for the further software study consid ering proppant embedment.