油页岩天然岩心支撑剂嵌入导流能力实验研究

Experimental Study on Conductivity with Proppant Embedment in Natural Oil Shale Core

辽河油田大民屯盆地沙四段发育一套湖相致密储层，岩性为含碳酸盐的油页岩。由于平均泥质含量高达39．4％，支撑剂容易发生嵌人使人工裂缝导流能力变差。以往导流能力评价实验通常采用钢板或人造岩心夹持支撑剂的方法，忽略了储层岩性的天然属性，实验数据参考性差。为了定量评价储层条件下支撑剂嵌入影响，利用钻井取心制备成天然岩板，并运用CDLY-2006水力压裂裂缝导流能力测试系统，进行了天然岩板、钢板长期导流能力对比实验．分析了不同粒径、不同闭合压力、不同铺砂浓度下的裂缝导流能力变化。结果表明，随着闭合应力的增大，不同粒径支撑剂的导流能力普遍呈下降趋势：支撑剂粒径越大、铺砂浓度越小，因嵌入作用损失的导流能力越大。天然岩板导流能力实验提供了模拟储层条件下的相对精确数据，为油页岩储层压裂方案设计提供了参考依据。

A set of lacustrine tight whose lithology is carbonate-bearing reservoir developed in Sha4 member of Damintun Basin in Liaohe Oilfield, oil shale.Because average mud content is up to 39.4%,the proppant is very easy to be embedded and resuhs in weaker conductivity of artificial fractures.In the past experiments of conductivity evaluation,the proppant was hold by the steel plate or artificial core ,and the experimental data was poor for reference for ignoring the natural properties of reservoir lithology.In order to quantitatively evalu- ate the influence of proppant embedment under reservoir conditions ,natural rock plate was prepared using drilled cores ,and long-term conductivity of natural rock plate and steel plate was compared by the experi- ments using CDLY-2006 hydraulic fracture conductivity testing system.The conductivity of the fractures under the conditions of different particle sizes, various closure pressure and different proppant concentration was ana- lyzed.The experiment result indicates that the conductivity of proppant with different particle sizes generally decreases with the increase of closure stress ;the conductivity loss is more due to embedment with larger par- ticle size and smaller concentration of the proppant.The experiment of conductivity for the natural rock plate provides relatively accurate data under simulated reservoir conditions,and provides a reference for fracturing scheme design of oil shale reservoir.