高磨地区灯四段碳酸盐岩储层酸压复杂裂缝导流能力优化研究

发布时间：2018-03-14 10:38

本文选题：复杂裂缝　切入点：导流能力　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：海相碳酸盐岩储层是全球油气资源储层的重要组成部分,其资源量约占全球油气资源总量的70%,探明油气可采储量约占50%。近年来,在四川盆地川中地区震旦系灯影组四段碳酸盐岩储层也取得了巨大的油气资源勘探发现。酸化压裂是碳酸盐岩油气藏增产和稳产的重要手段。但四川盆地川中地区震旦系灯四段碳酸盐岩储层表现出深层高温、岩性以白云岩为主、天然裂缝发育等特征,同时储层闭合压力高、酸液对裂缝壁面的非均匀刻蚀程度较差,如何评价酸压后的裂缝状态及酸压后不同支撑状态下的导流能力是该类储层酸压实现有效增产面临的难题。本论文从灯影组四段碳酸盐岩储层基本特征出发,重点关注其天然裂缝发育情况,建立了一套裂缝性碳酸盐储层酸压复杂裂缝形成可行性实验表征手段和酸压复杂裂缝导流能力测试方法。首先采用CT扫描技术,对岩样内部裂隙系统进行三维数值化重构,明确了天然裂缝在岩样中的展布特征,然后针对各个岩样中天然裂缝分布特征开展真三轴水力压裂实验,压裂后重构裂缝系统,对比分析了水力裂缝的扩展路径和形态以及天然裂缝对水力裂缝扩展的影响,进而分析了其形成复杂裂缝形态的可行性。同时,基于灯四段碳酸盐岩储层地质特征,建立了单井储层双重孔隙介质模型,研究了不同裂缝长度和导流能力对压裂井产能的影响,优化得到了经济产能下的裂缝导流能力。根据形成复杂裂缝可行性及形成的裂缝状态,以及优化得到的裂缝导流能力,开展了自支撑裂缝、酸刻蚀裂缝和酸加砂裂缝等三种裂缝支撑状态下不同滑移量、不同闭合压力、不同酸液浓度、不同支撑剂粒径和铺砂浓度条件下的导流能力测试实验研究。研究表明,高磨地区灯四段会诱导天然裂缝张开,同时产生部分剪切滑移裂缝,真三轴大型物模实验显示能够形成一定程度的复杂裂缝;从数值模拟和导流能力测试结果来看,形成的复杂裂缝系统中自支撑裂缝导流能力有限,酸刻蚀或酸加砂形成的主干裂缝才能满足产能需求;随着注酸排量的增加,酸蚀裂缝表面形态越复杂,目标储层闭合压力条件下导流能力越高;对于酸加砂支撑裂缝,导流能力随着支撑剂铺置浓度的增加而增加,但支撑剂铺置浓度过低(2kg/m2),酸加砂裂缝导流能力反而低于酸蚀裂缝导流能力,酸加砂裂缝存在临界加砂强度;此外,支撑剂粒径对导流能力的影响并不明显。建立的裂缝实验表征手段可为复杂裂缝形成可行性提供思路,同时酸压形成的三级支撑裂缝导流能力测试结果可为四川盆地碳酸盐岩油气藏改造方式提供指导。
[Abstract]:Marine carbonate reservoir is an important part of the global oil and gas resources reservoir, its resources account for about 70 percent of the total oil and gas resources in the world, and the proven recoverable oil and gas reserves account for about 500.In recent years, The carbonate reservoir of the fourth member of the Dengying formation of the Sinian system in Sichuan Basin has also been found in the fourth member of the formation. Acidizing fracturing is an important means of increasing production and stable production of carbonate reservoir. The carbonate reservoir of the fourth member of the Lantern formation of the Sinian system shows deep high temperature. The lithology is dominated by dolomite and the natural fractures are developed. At the same time, the closed pressure of the reservoir is high, and the non-uniform etching degree of acid to the fracture wall is poor. How to evaluate the fracture state after acid fracturing and the flow conductivity under different support states after acid compression is a difficult problem for this kind of reservoir to achieve effective production increase. This paper starts from the basic characteristics of carbonate reservoir in the fourth member of Dengying formation. Focusing on the development of natural fractures, a set of experimental methods for characterizing the feasibility of acid-fracturing complex fractures in fractured carbonate reservoirs and measuring the conductivity of acid-fracturing complex fractures are established. Firstly, CT scanning technique is used. The 3D numerical reconstruction of the internal fracture system of rock samples is carried out, and the distribution characteristics of natural fractures in rock samples are defined. Then the true triaxial hydraulic fracturing experiments are carried out according to the distribution characteristics of natural fractures in each rock sample, and the fracture system is reconstructed after fracturing. The propagation path and morphology of hydraulic fractures and the influence of natural fractures on the propagation of hydraulic fractures are compared and analyzed, and the feasibility of forming complex fracture forms is analyzed. At the same time, based on the geological characteristics of carbonate reservoirs in the fourth member of the lamp formation, The dual pore medium model of single well reservoir is established, and the influence of different fracture length and conductivity on the productivity of fracturing well is studied. According to the feasibility of forming complex fracture and the state of formation of fracture, and the optimized capacity of fracture diversion, the self-supporting fracture is developed. The experimental study on the flow conductivity under the conditions of different slip amount, different closing pressure, different acid concentration, different particle size of proppant and sand spreading concentration under three kinds of fracture supporting states, such as acid etching fracture and acid plus sand fracture, is studied. The four sections of lamp in Gaomo area can induce the natural crack to open, and at the same time produce partial shear slip crack. The true triaxial large-scale physical model experiment shows that the complex crack can be formed to a certain extent, and from the results of numerical simulation and flow conductivity test, The main fracture formed by acid etching or acid sand can meet the demand of productivity only when the flow conductivity of self-supporting fracture is limited in the complex fracture system, and the surface morphology of acid-etching fracture becomes more complex with the increase of acid injection discharge. The higher the conductivity of the target reservoir is under the condition of closed pressure, the higher the conductivity increases with the increase of the concentration of proppant for the acid sand supporting fracture. But when the concentration of proppant is too low, the conductivity of acid sand fracture is lower than that of acid corrosion fracture, and the critical sand adding strength exists in acid sand fracture. The influence of the particle size of proppant on the flow conductivity is not obvious. At the same time, the test results of three-stage supported fracture conductivity formed by acid fracturing can provide guidance for the transformation of carbonate reservoirs in Sichuan Basin.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.2

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