水平井分段压裂多裂缝扩展规律研究

发布时间：2018-03-11 19:38

本文选题：非常规油气藏　切入点：水平井　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国非常规油气储量丰富,已成为我国油气生产中的中坚力量,水平井分段多簇压裂是经济高效开发这类储层最关键的技术之一。水平井分段压裂多裂缝扩展时由于多裂缝受到应力干扰而导致其裂缝形态发生显著变化,严重影响着压裂效果和压后产量。因此迫切需要掌握水平井分段压裂多裂缝扩展变化规律,进而科学指导压裂施工设计,为我国非常规油气藏的高效开发提供技术支撑。本文从水平井分段压裂多裂缝同时起裂延伸的特点出发,首先在文献调研基础上综合考虑了裂缝诱导应力场、滤失诱导应力场、裂缝内流体流动、井筒中流体流动以及裂缝扩展准则等因素,建立了水平井多裂缝扩展数学模型。然后针对诱导应力场和流体压力场的不同特点,分别采用位移不连续法和有限差分法实现了流固耦合求解,对比了单裂缝扩展解析模型和现有多裂缝扩展数值模型,验证了本文模型的准确性。随后在本文模型基础上分析了单裂缝扩展形态、诱导应力场以及非平面扩展等变化规律,研究了多裂缝扩展过程中的裂缝形态、应力分布及流量分配等变化规律,并对多裂缝扩展的影响因素进行了分析。最后提出了基于裂缝形态定量表征裂缝均匀系数来反映多裂缝扩展均匀程度,在此基础上分析了地层参数对多裂缝扩展均匀程度的影响规律,优化了多裂缝扩展时的压裂施工参数,并根据建立的模型进行了现场实例应用。本文通过对水平井分段压裂多裂缝扩展规律的研究,取得的主要成果和认识如下:(1)单裂缝平面扩展时始终沿最大水平主应力方向延伸,产生的裂缝诱导应力场影响范围主要受到缝长和缝高的最小值控制;单裂缝非平面扩展时延伸方向逐渐偏向最大水平主应力方向,当初始裂缝方位角和主应力差越小时其裂缝形态越弯曲。(2)多裂缝扩展时外侧裂缝扩展较快且向外偏转,内侧裂缝扩展较慢且几乎不偏转;多裂缝之间地层受到的应力干扰较大;外侧裂缝的流量大于内侧裂缝。多裂缝扩展在低弹性模量、低压裂液排量、高裂缝簇间距、高压裂液黏度下易形成短宽缝。(3)针对多裂缝的非均匀扩展,提出了基于裂缝形态定量表征多裂缝扩展均匀程度的裂缝均匀系数。其值越大,多裂缝扩展均匀程度越高。多裂缝扩展时弹性模量越小、主应力差越小、裂缝簇间距越大、压裂液黏度越小、压裂液排量越大、孔眼数量越小、孔眼直径越小时都会促使其裂缝均匀系数越大,多裂缝扩展得越均匀。(4)以裂缝均匀系数为目标函数优化了多裂缝扩展时压裂施工参数。通过相对增加中间裂缝孔眼直径和孔眼数量可提高多裂缝扩展均匀程度;均质储层等簇间距布缝比非等簇间距布缝的裂缝扩展均匀程度更高;在各簇射孔参数相同时3簇裂缝最优簇间距为30～40m,当相对增加中间裂缝孔眼直径后其最优簇间距可降低为20～30m。本文对水平井分段压裂多裂缝扩展规律进行了深入研究,建立的数学模型可定量分析多裂缝扩展形态变化规律,提出的裂缝均匀系数能优化多裂缝扩展压裂施工参数。本文的研究成果对水平井分段多簇压裂优化设计具有一定的指导意义。
[Abstract]:China's unconventional oil and gas reserves, has become the backbone of China's oil and gas production, horizontal well fracturing of segmented multi cluster economic and efficient development of this kind of reservoir is one of the most critical technologies. The horizontal well fracturing multi crack due to stress interference by multiple cracks due to the crack shape change and seriously affect the fracturing effect and pressure after production. There is an urgent need to master the horizontal well fracturing multi crack propagation regularity, and scientific guidance of fracturing design, provide technical support for the efficient development of China's unconventional oil and gas reservoirs. This paper from the horizontal well fracturing cracks and crack extension characteristics of firstly, on the basis of literature research considering the fracture induced stress field, the filtration induced stress field, the fluid flow in fracture, wellbore fluid flow and crack propagation criterion and other factors, established level The mathematical model of well crack expansion. Then according to different characteristics of induced stress field and fluid pressure field, respectively by displacement discontinuity method and finite difference method, the fluid solid coupling solution, compared to the single crack propagation analysis model and the existing multi crack propagation numerical model, verified the accuracy of this model. Then based on in this paper, the model analysis of a single fracture shape, induced by the stress field variation law and non planar propagation, fracture morphology of multi crack propagation process. The variation of stress distribution and flow distribution, and the joints of expansion are analyzed. Finally, the multi crack crack morphology quantitative uniformity coefficient characterization of cracks to reflect the expansion of multi fractures based on uniform degree, based on the analysis of formation parameters on multi crack propagation influence of uniformity, optimization of multi crack propagation when the pressure Crack construction parameters, and an instance of the application site according to the established model. Based on the research of horizontal well fracturing multi crack propagation law, the main results are as follows: (1) single crack extension plane along the direction of maximum principal stress, stress field effect is mainly affected by the crack length and the minimum control of high seam induced crack; single non planar fracture extension extension direction gradually turn to the direction of maximum horizontal principal stress, when the initial crack angle and principal stress difference is the more hours crack shape bending. (2) multi crack propagation when lateral crack fast and outward deflection, inner cracks extended slowly and almost no deflection; many cracks between the formation of stress interference; lateral fracture flow rate is greater than the inner crack. Multi crack propagation in low elastic modulus, low fracture fluid displacement, high crack cluster spacing, High pressure fracturing fluid viscosity tends to form short wide slot. (3) for non uniform expansion cracks, puts forward the uniform crack crack shape coefficient of expansion based on quantitative characterization of uniformity. Its value is, the higher the degree of uniformity of multi crack propagation. Multi crack propagation when the elastic modulus is small, the main stress the smaller the difference, the greater the crack cluster spacing, the smaller the viscosity of fracturing fluid, fracturing fluid displacement is larger, smaller hole number, hole diameter more hours can bring about the crack of uniform coefficient is, the more uniform expansion of multi fractures. (4) with uniform coefficient as the objective function to optimize the multi crack crack construction parameters fracture propagation. The relative increase in the number of cracks in the middle hole diameter and hole can improve the uniformity of multi crack propagation; homogeneous reservoir cluster spacing cloth cracks etc. non cluster spacing cloth expansion is more uniform; in each cluster same perforation parameter 3 cluster cracks Optimal cluster spacing is 30 ~ 40m, when the relative increase of cracks in the middle hole diameter after optimal cluster spacing can be reduced to 20 ~ 30m. of the horizontal well fracturing multi crack propagation regularity is studied, the mathematical model established by quantitative analysis of multi crack propagation regularity of crack morphology, uniform coefficient is proposed to optimize multiple cracks extended fracturing parameters. The research results of this multi cluster fracturing optimization design has a certain guiding significance for the horizontal well section.

【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

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