【作者】 孙志宇；

【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】 为进一步提高水平井的产量和最终采收率,改善开采的经济效益,本文对水平井多级脉冲气体加载压裂展开了系统的研究与应用,并编制相关软件对压裂水平井进行方案优化设计,具有重要的科学意义与明确的应用前景。从优化方法出发本文研究内容与主要成果为:(1)根据水平井的结构特点,对多级脉冲加载压裂装置和延时控制装置在井筒中的作用特点进行了分析,设计出了合理的装药结构,并评价了该技术的安全可靠性。(2)根据弹性力学理论和断裂力学理论,在裸眼完井、射孔完井条件下,建立了爆燃压裂水平井井筒周围应力场分布的新模型以及裂缝起裂压力和起裂角的计算模型,并进行了求解。(3)通过设计室内冲击实验模拟多级脉冲爆燃气体压裂等强动载条件对油气水井附近油层的处理。对比了动载破裂压力与静载破裂压力的差值、动静载破裂压力差值与抗拉强度的比值、动载破裂压力与静载破裂压力的比值四个物理量与加载速率关系,根据实验数据数值回归动载、静载破裂压力表达式,以修正爆燃压裂水平井起裂压力。(4)根据爆燃压裂水平井井下工作条件,参考流体质量、动量和能量守恒方程建立裂缝内爆燃气体流动模型;采用设定裂缝内气体压力分布函数的方法,实现流动模型的数值求解;在岩石弹性理论下,建立了多级脉冲压裂作用下水平井预存裂缝起裂张开位移公式;根据叠加原理推导了水平井爆燃压裂各项荷载作用下裂缝尖端应力强度因子,建立裂缝延伸判据,利用裂尖能量守恒方程确定裂缝扩展速度;将多级脉冲压裂气体响应模型与气体流动模型相结合,实现了爆燃气体流动和裂缝扩展藕合求解;根据具体储层、施工参数对水平井多级脉冲气体加载压裂中各级压裂过程进行了模拟计算,确定具体的裂缝形态;利用能量平衡理论反映裂缝动态扩展的特性,并对多级脉冲与单级脉冲作用效果进行了对比。(5)利用建立的数学模型开发水平井多级脉冲气体加载压裂模拟计算软件,并对影响水平井爆燃压裂效果的主要因素展开了系统的数值优化设计,分析了不同裂缝参数对产能的影响,为现场施工提供指导。(6)进行了多级脉冲气体加载压裂水平井的井下压裂施工设计及效果预测,研究了该工艺技术在水平井下的操作流程及压裂后产能对比,为进一步的现场应用奠定了基础。更多还原

【Abstract】 In order to enhance the production of horizontal well and improve the economic benefit of development,the multi-pulse gas loading fracturing on horizontal well is studied and applied and a relative stimulating soft ware is also developed to optimize the fracturing in this paper, which is of great significance for scientific research and field application . Based on the fracturing horizontal well technology need, the main achievements in this paper can be concluded as follows:(1) Analyzing the devices of multi-pulse gas loading fracturing and flame ignition that related to horizontal well,this paper designs reasonable propellant charge,analyses the characteristics of this technology and evaluates its secrity and reliability.(2) According to the theory of elastic mechanics and fracture mechanics under deflagration gas loading fracturing ,established the mathematical model of the stress field distribution around the horizontal well bore and the model of fracturing pressure and fracturing angle for open-hole and perforated well.The modeling can be solved and provides the reliable theoretical evidence for fracturing treatment of horizontal well.(3) Based on the flow behavior of deflagration gas in horizontal oil well, a theoretic model of detonation gas flow in preliminary crack is established, by means of introduction of a pressure distribution function concluded from analytic result of gas flow along the crack.(4) The crack opening displacement is also modeled by referencing relationship between crack normal displacement and pressure along the crack in multi-pulse gas loading fracturing model.The stress strength factor at the crack tip is deduced to estimate fracture initiation.Energy release rate obtained by J-integral at the crack tip is used to determine the crack spread velocity after fracture initiation. Coupling process between detonation gas flow and crack spread is also simulated based on the combination of the solid一fluid governing equations,which can be solved to moldeling the fracture geometry and pressure distribution along the fracture of each stage. As allow for rapid fracture process driven by detonation gas,kinetic energy increment is further introduced into energy conservation equation at the crack tip.(5) The results from this numerical model agree with corresponding results from half-analyzed and concrete column test. Aim at the fracture length which is main factor in oil well to relate the production, several primary factors are systematically discussed by numerical test to find out the most effective measures fracturing works. in horizontal well.This paper also derives the formulae to estimate the productivity increase achieved by muitiple fractures and discusses the main factor of influence.(6) The method of muti-pulse gas loading fracturing on horizontal well is disscussed,which studies the operating processes of this technique under down-hole condition and productivity contrast after fracturing to lay the groundwork for the future field application.更多还原