水平井定面射孔水力压裂数值模拟研究

发布时间：2018-07-07 16:50

本文选题：水平井 + 定面射孔　；参考：《西安理工大学》2017年硕士论文

【摘要】：水平井定面射孔技术是一种新型的射孔技术。水平井可以通过改变穿过油层的方位来避免穿透复杂地形,从而降低了实施的难度,定面射孔技术可以通过调节射孔弹的布弹方式,从而获得最优破裂面,扩大裂纹区域,降低岩石的起裂压力,科学的引导裂缝走向。与常规射孔和单一射孔相比,定面射孔可以减小岩石的破裂压力,增加岩石的破裂区域,减小地层的破坏,增加其稳定性,提高石油的产量。本文采用最大拉应力原理结合数值模拟的方法,对水平井定面射孔水力压裂岩石起裂进行研究。本文主要从以下几个方面进行研究分析:首先,本文利用有限元软件Abaqus 6.14对不同地应力,射孔夹角(15°, 30°,45°,60°,75°,90°),射孔尺寸(射孔直径,射孔深度)等影响因素的研究以及对预测裂纹区域(1.同一夹角,不同压裂液压力;2.同一压裂液压力,不同夹角)的分析,得出不同影响因素下,岩石起裂压力的变化规律。通过模拟得出:(1)在不同的地应力状态下,岩石的起裂压力不同,第一种地应力场情况下所需要的起裂压力最大,第三种地应力场次之,第二种地应力场情况下所需要的起裂压力最小,其中,最大水平主应力和最小水平主应力的变化对岩石的起裂压力也有所影响。(2)地应力大小相同的情况下,三种地应力状态所得出的结果相同,岩石的起裂压力都是随着射孔夹角增大而增加。(3)只改变射孔直径增加,起裂压力呈减小趋势,随着射孔长度的减小起裂压力也呈减小趋势。(4)同一压裂液压力,改变射孔间的夹角,当射孔夹角为60°时,射孔间裂缝扩展区域、射孔间距、相邻射孔裂缝扩展融合区域都是最合适的,最终裂缝扩展融合面积最大,45°时较次之;同一射孔夹角,由于压裂液压力的增大,应力在射孔孔眼之间相互作用,裂缝最初发生在射孔与井筒的交界处,随后相互贯通,最后形成扇形预测破裂面。其次,三种射孔弹型从岩石的起裂压力与预测裂纹区域两方面进行对比分析,三种射孔弹类型分别为: 1#射孔弹:孔径10.4mm,孔深660nm; 2#射孔弹:孔径11.0mm,孔深876mm; 3#射孔弹:孔径16.9mm,孔深646mm。得出2#射孔弹型最优。最后,采用有限元软件Abaqus 6.14对单一射孔、常规射孔和定面射孔进行对比分析。(1)对不同射孔方式下岩石的起裂压力进行对比:单一射孔,主要研究了角度由0°变化到90°时,岩石的起裂压力;常规射孔,只对射孔孔眼间距沿Y轴分别为6cm/24cm/6cm的一种情况进行研究;(2)对比三种射孔在同一压裂液压力(40MPa,60MPa)下,预测裂纹区域面积的对比。结果表明:定面射孔相对于前两种射孔方式,在降低起裂压力与预测裂纹区域方面都具有一定的优势。由上述研究分析,本文从如何降低岩层的破裂压力入手,主要研究了不同影响因素下,岩石的起裂压力的变化规律,从而将定面射孔进行优化。
[Abstract]:Horizontal well fixed-plane perforation technology is a new type of perforation technology. Horizontal well can avoid penetrating complex terrain by changing the direction of passing through the reservoir, thus reducing the difficulty of implementation. The fixed plane perforation technology can obtain the optimal fracture surface and expand the crack area by adjusting the method of projectile distribution. Reduce the initiation pressure of rock and guide the fracture direction scientifically. Compared with conventional perforation and single perforation, fixed plane perforation can reduce rock fracture pressure, increase rock fracture area, reduce formation damage, increase stability and increase oil production. In this paper, the maximum tensile stress principle and numerical simulation method are used to study the fracture initiation of hydraulic fracturing rock with fixed plane perforation in horizontal well. This paper mainly studies and analyzes the following aspects: firstly, this paper uses finite element software Abaqus 6.14 to deal with different in-situ stress, perforation angle (15 掳, 30 掳(45 掳) 60 掳60 掳(75 掳) 90 掳), perforation size (perforation diameter). Study on influencing factors such as perforation depth and prediction of crack area (1. At the same angle, different fracturing fluid pressure is 2. According to the analysis of the same fracturing fluid pressure and different angle, the variation law of rock initiation pressure is obtained under different influence factors. The simulation results show that: (1) under different in-situ stress states, the initiation pressure of rock is different, the first kind of in-situ stress field requires the biggest initial crack pressure, the third kind of in-situ stress field is the second. The change of maximum horizontal principal stress and minimum horizontal principal stress also affect the initiation pressure of rock. (2) under the same magnitude of in-situ stress, the initiation pressure of rock is the smallest, and the variation of maximum horizontal principal stress and minimum horizontal principal stress also affect the initiation pressure of rock. (2) under the condition of the same magnitude of in-situ stress, The results obtained from the three in-situ stress states are the same. The initiation pressure of rock increases with the increase of perforation angle. (3) the diameter of perforation increases and the initiation pressure decreases. With the decrease of perforation length, the initiation pressure also decreased. (4) when the angle of perforation was 60 掳, the fracture spread area and perforation distance between the perforations were changed with the same fracturing fluid pressure. The area of adjacent perforation fracture propagation and fusion is the most suitable, and the final fracture propagation fusion area is the second when the maximum area is 45 掳, and the stress interaction between perforating holes is due to the increase of fracturing fluid pressure at the same perforation angle. The fracture occurred at the junction of perforation and wellbore, and then intersected with each other, and finally formed the fan-shaped predicted fracture surface. Secondly, three types of perforated projectiles are compared and analyzed from two aspects: the initiation pressure of rock and the prediction of crack area. The three types of perforating projectile are: 1# projectile with an aperture of 10.4mm and hole depth of 660nm; 2# projectile with an aperture of 11.0mm and a hole depth of 876mm; and a perforator with an aperture of 16.9mm and a hole depth of 646mm. The optimum perforating projectile type is obtained. Finally, the finite element software Abaqus 6.14 is used to compare and analyze single perforation, conventional perforation and fixed plane perforation. (1) the crack initiation pressure of rock under different perforation modes is compared: single perforation, when angle changes from 0 掳to 90 掳, is studied. The fracture initiation pressure of rock and conventional perforation are studied only when the perforating hole spacing is 6cm/24cm/6cm along Y axis, and (2) the comparison of three perforating fluid pressure (40MPA ~ (60 MPA) in predicting the area of crack area is made. The results show that the fixed plane perforation has some advantages in reducing the initiation pressure and predicting the crack area compared with the first two perforation modes. Based on the above research and analysis, this paper starts with how to reduce the fracture pressure of rock, and mainly studies the variation law of the initiation pressure of rock under different influence factors, so as to optimize the fixed plane perforation.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE257.1;TE357.1

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