【作者】 吴飞鹏；

【导师】 蒲春生；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2009， 博士

【摘要】 高能气体压裂系统关键因素理论研究的欠缺,严重限制了该技术在油田的进一步推广。论文首先对高能气体压裂过程中的火药爆燃加载、压挡液柱运动、裂缝动态延伸三个主要模块进行了动力学模型和相应求解方法的研究。其中火药爆燃加载模型是在火药燃速模型的基础上,综合气体状态方程、质量守恒方程、能量守恒方程而建立的;压挡液柱运动模型是假设了火药燃气与压挡液之间存在完全接触界面,由连续性方程、动量守恒方程、能量守恒方程组成,可考虑液柱的动能分布和管柱摩擦作用的影响;裂缝动态延伸模型是在现有理论的基础上,利用质量守恒和能量守恒理论耦合了孔眼泄流、缝内流体压力分布、缝壁渗漏、裂缝延伸判据和裂缝形态计算五个子模型而组建的。同时论文在完善了考虑井筒内压影响的套管射孔井周围应力分布模型的基础上,分别利用理论推导和岩石冲击破坏实验,得出了可保障套管安全和顺利压开油层的极限压力计算模型,为高能气体压裂各子系统间的耦合提供了衔接条件。其中套管安全校核模型考虑了套管受压过程中壁面径向位移和射孔孔眼的影响,而强动载下岩石破裂压力模型是利用“岩石动态损伤模拟实验装置”直接对小型模拟井眼进行高能气体压裂加载条件下的冲击破岩实验,回归得出其与加载速率、静载下破裂压力间的高精度计算相关式。在建立和完善了高能气体压裂过程中三个子系统模型及其衔接条件的基础上,建立了由各子系统中压力、温度为主线变量的质量守恒方程和能量守恒方程,再结合各子模型的求解方法,研究了高能气体压裂全过程的耦合求解技术,并进行了应用软件的研制。据此既可定量计算合理的装药量范围,也可对高能气体压裂的爆燃压力、裂缝形态进行定量动态预测;并以此为基础,研究了高能气体压裂中各子系统自身的动态变化规律以及装药结构、装药质量、压挡液高度、射孔密度、射孔孔径五个关键参数对压裂效果的影响敏感性。最后通过对高能气体压裂现场井的工艺参数优化设计和措施效果分析,结果表明论文所建立的高能气体压裂系统动力学模型和相关应用软件具有较强适用性和准确性,可为该技术的进一步推广提供一定的理论支持。更多还原

【Abstract】 The theoretical research deficiency of the key elements to High Energy Gas Fracture (HEGF) system has greatly restricted its further popularity and application in oilfield. First, the dynamic models and relative solution methods of the three major subsystems, including deflagrating powder loading, liquid column movement above the powder gas and fracture dynamic extension are studied. Based on the powder combustion rate model, the powder deflagrating load model is built using the ideal gas state equation, mass conservation equation and energy conservation equation. On the assumption that there exists a complete contact interface between the powder gas and the liquid column above, the liquid column movement model constituted by continuity equation, momentum conservation equation and energy conservation equation is established, which can take into consideration of the effect of liquid column’s kinetic energy distribution and string friction. By coupling the five sub models such as perforation releasing, liquid pressure distribution in fracture, liquid seepage around fracture plane, fracture extension criteria and fracture shape calculation, the fracture extension model is built utilizing mass conservation theory and energy conservation theory. At the same time, based on the improvement of the stress distribution model of casing perforated well considering within the wellbore pressure effect, the limit pressure calculation models which can guarantee casing safe and oil layer’s easily cracking is established by theoretical study and the rock shocking damage experiments separately, which can afford a joint qualification for the HEGF’s subsystems coupling. And the casing safe checking model can take into consideration of casing wall radial displacement and perforation effect in the process of casing pressuring.And the rock cracking pressure model under Strong dynamic loading condition is a high accuracy relational expression among dynamic fracturing pressure, static fracturing pressure and loading rate, which is regressed according to the rock impact damage experiments to small scale simulation wellbore, using the“rock dynamic damage simulation experimental device”. On the basis of the established and improved models of all subsystems and their joint qualifications to HEGF process, the mass conservation equations and energy conservation equations which are correlated by pressure and temperature of all subsystems are built, and then combing the resolving methods of all sub models, the whole process couple calculating technology is formed and the related software is programmed. According to the calculating technology and the application software, the reasonable powder charge bound can be quantitatively calculated and the deflagrating pressure and the fracturing patterns under different parameters values can be accurately predicted. Based on this, the dynamic changes of the three subsystems to the HEGF process are studied, and the sensitivities to fracturing effect of five key parameters including powder structure, powder amount, height of liquid column above the powder gas, perforation density and perforation diameter are analyzed. Finally, the parameters optimization design and the application results of an oilfield HEGF well show that the HEGF system dynamic model and related application software given by this dissertation have strong applicability and accuracy, which can support the HEGF’s further popularization and application.更多还原