砾岩油藏岩石力学特征及其对压裂改造的影响

Rock mechanics characteristics of conglomerate reservoir and its effects on fracturing treatment

砾岩油藏常利用压裂改造提高产能,而油藏岩石力学性质是压裂改造设计的基础。因此,以砾岩储层岩石为研究对象,采用物理实验和数值模拟相结合的方法,研究了玛湖凹陷砾岩油藏的岩石力学特征及其对压裂改造的影响。结果表明:砾石压入硬度与岩性有关,高强度、较大尺寸的砾石能有效抑制裂缝穿透砾石,强化砾岩整体的抗拉强度;储层强水平应力差是实现压裂裂缝横向延伸的助力因素,从提高油井产能角度来看,对于物性较好的储层,应以扩大改造规模、实现压裂裂缝横向延伸为目的,而对于物性较差的储层,应以形成复杂的缝网结构为目的,在弱水平应力差的砾岩储层进行压裂改造。研究结果对于认识砾岩地层裂缝扩展机理、细分压裂改造措施具有重要的意义。

In order to increase productivity,conglomerate reservoirs are often fractured,however,the rock mechanics properties of the reservoir are the basis of fracturing design.Therefore,taking conglomerate reservoir rocks as the research object,a method combining physical experiment and numerical simulation was used to study the rock mechanics characteristics of conglomerate reservoir and its effects on fracturing in Mahu Sag.The results show that the hardness of gravel is related to lithology.High-strength and larger-size gravel can effectively inhibit cracks from penetrating the gravel and strengthen the overall tensile strength of the conglomerate.A strong horizontal stress difference of the reservoir is a contributing factor to realize the lateral extension of fractures.From the perspective of improving the productivity of oil wells,for reservoirs with good physical properties,the goal should be to expand the scale of fracturing and realize the lateral extension of fractures,while for reservoirs with poor physical properties,the goal should be to form a complex fracture network structure,and fracturing is carried out in the conglomerate reservoir with weak horizontal stress difference.The research results are of great significance for understanding the mechanism of fracture propagation in conglomerate formations and subdivision of fracturing measures.