【作者】 贺慧；

【导师】 陈德春；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2009， 硕士

【摘要】 我国石油工业目前后备储量紧张,探明未动用石油地质储量中大部分为低渗透储量,为了有效动用低渗透油田的储量,油层强动载造缝技术得到了广泛应用,但油层强动载造缝过程影响因素分析、造缝过程动态分析以及裂缝条数预测等的研究缺乏,影响着技术的进一步发展。针对这一问题,利用火药燃烧模型、质量守恒方程和能量守恒方程,推导了火药在定容积内强动载加载过程的压力、温度随时间变化的加载计算模型;根据井筒内的散热损失,建立了爆燃后卸载的温度、压力变化模型,分析了装药质量、装药结构、初始空间体积和初始空间压力等对火药爆燃过程的压力、温度的影响规律;运用断裂理论,基于裂缝受力分析,引入地层岩石断裂动态应力强度因子,建立了油层强动载作用下破裂压力计算模型;结合高压流体在裂缝中的压力分布近似模型、流体渗滤模型、裂缝起裂/止裂判据模型、裂缝延伸速度模型、延伸宽度模型及裂缝体积计算模型,利用质量守恒和能量守恒,建立了裂缝动态延伸的数学模型;综合上述各子模型,建立了火药爆燃—地层开裂—裂缝延伸的强动载造缝动态模拟模型,编制了计算软件,并进行耦合求解。结果表明:缝长和缝宽均随时间迅速增长;峰值压力和造缝长度均随裂缝条数的增加而降低,一定条件下当裂缝条数从2增加到6时,峰值压力从108.4MPa降至63.6MPa,裂缝长度由2.48m减至1.17m。利用“岩石动态损伤模拟实验装置”作了24组实验,实验研究表明加载速率是影响裂缝条数的主要因素;根据强动载造缝耦合模型计算了不同火药参数下的加载速率、峰值压力与裂缝条数,并回归出加载速率与裂缝条数的关系式,与实验所得的关系式进行了对比分析,结果吻合较好;因此逐步推得不同装药量、装药结构与裂缝条数的指数回归关系式,并达到一定精度,从而建立了强动载造缝裂缝条数数学模型。强动载造缝动态模拟模型的建立与研究,为这类技术工艺参数设计和控制提供依据,对这类技术的发展和应用具有重要的指导意义。更多还原

【Abstract】 Our country’s petroleum industry development now are facing embarrassing and pressing phenomenon that is the shortage of the back up reserves and the majority of the proved unexploited reserves being reserves of low permeability. Reservoir strong dynamic load fracture initiation technology has been popularized in order to effectively exploit low permeability reserves. Nowadays researches on process parameters analysis, process dynamic analysis and fracturing numbers analysis of strong dynamic load fracture initiation technology are limited which greatly restrict the technology’s further development. Focusing on these problems, some work has been done in this paper. Firstly, the loading calculation model of pressure’s and temperature’s variation with time in the stable cubage powder’s loading process. Then, on the basis of wellbore heat loss theory, the temperature and pressure variation model after deflagrating is conducted with the affecting law analysis of powder amount, powder holding structure, initial space volume and initial space’s pressure to the pressure and temperature in powder deflagrating process. Thirdly, ground rock fracturing dynamic stress strength factor is introduced and thus reservoir fracturing pressure calculation model under strong dynamic condition is proposed after fracture’s force analysis using fracturing theory. Fourthly, by utilizing mass and energy conservation equation, the mathematical model of fracture extension is built by coupling the following models including pressure distribution model of high pressure liquid in fracture, liquid seepage model, fracture beginning and ending criterion model, fracture extension rate model, fracture extension width model and fracture volume model. Then, by interconnecting all the sub models, the strong load fracturing dynamic simulation model connecting powder deflagrating, ground fracturing and fracture extension is built and the related computational software is programmed to carry on model coupling calculation. The results show that: the fracture’s width and length increase with time; both peak pressure and fracture length will decrease with fracture number’s increasing, for example, the peak pressure decreases to 63.6MPa from 108.4MPa and fracture length decreases to 1.17meters from 2.48 meters when fracture number increases to 6 from 2. Using“rock dynamic damage simulation experimental setup”, 24 tests are made and the experiment results show that loading rate is the major factor that affects fracture number; the loading rate, peak pressure and fracture number under different powder parameters are calculated and the relationship equation between loading rate and fracture number is regressed which shows satisfactory inosculation when compared with the equation got from experiment. The exponential equations between fracture number and powder amount as well as powder holding structure are gained and can reach a satisfying accuracy. In this meaning, the fracture number model under strong load condition is gained. The building and research of strong load dynamic fracturing model have provided criterion of the technology’s parameters’design and control, and has an important guiding meaning to the technology’s further improvement and application.更多还原