支撑剂嵌入及对裂缝导流能力损害的实验

对于岩石较软的地层，在压裂过程中的支撑剂嵌入会降低压裂充填后的裂缝宽度，同时嵌入区地层碎屑也会损害支撑剂充填层的导流能力，因而有必要对支撑剂的嵌入进行研究，并为压裂施工中的支撑剂优选提供依据。为此，运用API标准导流室和基于API标准导流室自行研制的测试仪器，对地层岩心的支撑剂嵌入情况进行了实验研究，并在支撑剂嵌入的基础上，考虑了地层碎屑对裂缝导流能力损害的影响。在国内首次对支撑剂嵌入后的岩心进行了微观分析，更加直观地反映了嵌入程度和嵌入状态。实验考察了不同铺砂浓度、不同压力下对不同岩心的支撑剂嵌入情况。实验表明：由于支撑剂的嵌入，会使支撑裂缝宽度有较大程度的减小；铺砂浓度越低，地层岩石越软，嵌入越严重。还模拟了支撑剂嵌入后不同碎屑浓度对同一种岩心的导流能力伤害程度，并发现在嵌入后的碎屑达到一定浓度后会直接堵塞孔道。

EXPERIMENTAL RESEARCH ON PROPPANT EMBEDMENT AND ITS DAMAGE TO FRACTURES CONDUCTIVITY

For the strata with relatively soft rocks, proppant embedment in the process of fracturing will reduce the fracture width after frac packing, and at the same time, the debris of embedded formation can damage the conductivity of proppant filling beds. Therefore, it is necessary to study on the embedment of proppant, so as to provide a basis for the selection of proppant in the process of fracturing operation. For this reason, an experimental research on proppant embedment in cores was carried out by use of API standard instrument and self developed instrument based on API standard instrument. Moreover，on the basis of proppant embedment, this study also took into account the damage of the debris to the fractures' conductivity. It was the first time in China for microcosmic analysis on the cores to be carried out after proppant embedment, so that the degree and state of embedment could be reflected much more intuitively. In experiments, studies were performed on the embedment of proppant in different cores under different sanding concentrations and stresses. Experiments indicated that, due to the embedment of proppant, the width of propped fracture could be significantly reduced; the smaller the sanding concentration and the softer the core was, the greater level of embedment would be. Moreover, by simulating the damage level of flow conductivity towards the same kind of core in different debris concentrations after the proppant embedment, it was discovered that after the embedment the pore channel would be blocked as the debris concentration reaches a certain degree.