近井多分支缝压裂起裂机理有限元模拟研究
发布时间：2018-08-19 21:00
【摘要】：海拉尔油田属于复杂断块油田,部分区块储层物性差,水井压裂后仍难以实现有效注入。因此,开展了低产井压裂提高单井产量技术研究很有必要。而常规压裂形成的对称双翼裂缝改造体积有限,不能充分动用致密油气资源,多分支压裂技术可有效解决上述问题。但目前对近井多分支压裂技术的起裂机制及影响因素认识不清,为此本文运用有限元方法,利用comsol软件对多分支缝起裂机理进行模拟研究,主要工作及认识如下:1、考虑初次压裂诱导应力对近井地带应力场的作用,建立多分支缝起裂角及起裂压力的力学计算模型。应用有限元软件实现了近井区域裸眼井眼压裂机理、全尺寸单缝压裂机理、近井区域单缝压裂机理、近井区域多分支缝压裂机理的数值模拟分析。2、根据有限元数值模拟结果,确定了初始缝的起裂点、第一条分支缝、第二条分支缝的起裂点和净压力。3、初始缝的起裂点在井壁上,且垂直于最小水平主应力,符合经典理论观点。该起裂点称为起裂点1A。第一条分支缝在初始缝尖端、初始缝缝体中部和井眼上。三个起裂点分别定义为2A、2B、2C。在第一条分支缝全堵和局部半堵时,端部的应力集中是不存在,即起裂点2C不存在。在初始缝全堵条件下,第一条分支缝在初始缝全堵柔性支撑区中部和井眼上起裂。在初始缝半堵条件下,第一条分支缝在初始缝全堵柔性支撑区到井眼的中部和井眼上起裂。4、第二条分支缝在井眼上、第一条分支缝缝体中部、初始缝缝体中部、第一条分支缝尖端。五个起裂点分别定义为3A、3B、3C、3D、3E。在第二条分支缝全堵和局部半堵时,端部的应力集中是不存在,即起裂点3D和3E不存在。此时第二条分支缝在井眼上的起裂点3A和裂缝中部的起裂点3B和3C起裂或者延伸。
[Abstract]:Hailaer oilfield belongs to complex fault block oilfield, some blocks have poor physical properties, and it is still difficult to realize effective injection after well fracturing. Therefore, it is necessary to study the technology of fracturing and improving single well production in low production wells. However, the symmetrical double-wing fracture formed by conventional fracturing is limited in volume and can not fully utilize dense oil and gas resources. The multi-branch fracturing technology can effectively solve the above problems. However, there is no clear understanding of the fracture initiation mechanism and its influencing factors in the near well and multi-branch fracturing technology. In this paper, finite element method is used to simulate the fracture initiation mechanism of multi-branched fractures using comsol software. The main work and understanding are as follows: 1. Considering the effect of the initial fracturing induced stress on the stress field in the near well zone, the mechanical calculation model of the fracture initiation angle and the initiation pressure of the multi-branch fractures is established. Using finite element software, the mechanism of open hole fracturing in near-well region, the mechanism of full-size single fracture fracturing, and the mechanism of multi-branch fracture fracturing in near-well area are analyzed by numerical simulation. 2. According to the results of finite element numerical simulation, The starting point of initial fracture, the first branch joint, the starting point and net pressure of the second branch joint are determined. The starting point of initial fracture is on the shaft wall and perpendicular to the minimum horizontal principal stress, which is in line with the classical theory. The starting point is called the initiation point 1A. The first branch is at the tip of the initial fracture, the middle of the initial fracture and the hole. The three initiation sites are defined as 2An 2BX 2C respectively. When the first branch joint is completely plugged and partially plugged, the stress concentration at the end of the joint does not exist, that is, the initiation point 2C does not exist. Under the condition of full plugging of initial fracture, the first branch fracture starts to crack in the middle of the flexible support area of the initial fracture. Under the condition of half plugging of initial fracture, the first branch fracture starts at the middle of the initial fracture and on the middle of the hole, the second branch fracture on the hole, the first branch fracture at the middle of the first branch fracture, the middle of the initial fracture body, and the middle of the initial fracture body. The first branch seams the tip. The five initiation sites are defined as 3An 3BX 3CX 3DX 3E respectively. When the second branch joint is completely plugged and partially plugged, the stress concentration at the end of the joint does not exist, that is, the initiation point 3D and 3e do not exist. The starting point 3A of the second branch fracture on the hole and the starting point 3B and 3C of the middle of the fracture begin or extend.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357
，
本文编号：2192818
[Abstract]:Hailaer oilfield belongs to complex fault block oilfield, some blocks have poor physical properties, and it is still difficult to realize effective injection after well fracturing. Therefore, it is necessary to study the technology of fracturing and improving single well production in low production wells. However, the symmetrical double-wing fracture formed by conventional fracturing is limited in volume and can not fully utilize dense oil and gas resources. The multi-branch fracturing technology can effectively solve the above problems. However, there is no clear understanding of the fracture initiation mechanism and its influencing factors in the near well and multi-branch fracturing technology. In this paper, finite element method is used to simulate the fracture initiation mechanism of multi-branched fractures using comsol software. The main work and understanding are as follows: 1. Considering the effect of the initial fracturing induced stress on the stress field in the near well zone, the mechanical calculation model of the fracture initiation angle and the initiation pressure of the multi-branch fractures is established. Using finite element software, the mechanism of open hole fracturing in near-well region, the mechanism of full-size single fracture fracturing, and the mechanism of multi-branch fracture fracturing in near-well area are analyzed by numerical simulation. 2. According to the results of finite element numerical simulation, The starting point of initial fracture, the first branch joint, the starting point and net pressure of the second branch joint are determined. The starting point of initial fracture is on the shaft wall and perpendicular to the minimum horizontal principal stress, which is in line with the classical theory. The starting point is called the initiation point 1A. The first branch is at the tip of the initial fracture, the middle of the initial fracture and the hole. The three initiation sites are defined as 2An 2BX 2C respectively. When the first branch joint is completely plugged and partially plugged, the stress concentration at the end of the joint does not exist, that is, the initiation point 2C does not exist. Under the condition of full plugging of initial fracture, the first branch fracture starts to crack in the middle of the flexible support area of the initial fracture. Under the condition of half plugging of initial fracture, the first branch fracture starts at the middle of the initial fracture and on the middle of the hole, the second branch fracture on the hole, the first branch fracture at the middle of the first branch fracture, the middle of the initial fracture body, and the middle of the initial fracture body. The first branch seams the tip. The five initiation sites are defined as 3An 3BX 3CX 3DX 3E respectively. When the second branch joint is completely plugged and partially plugged, the stress concentration at the end of the joint does not exist, that is, the initiation point 3D and 3e do not exist. The starting point 3A of the second branch fracture on the hole and the starting point 3B and 3C of the middle of the fracture begin or extend.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357
，
本文编号：2192818
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