【作者】 蒋金宝；

【导师】 韩志勇；

【作者基本信息】 中国石油大学 ， 油气井工程， 2008， 博士

【摘要】 随着石油工业的发展,低渗透油田在石油开发中的地位越来越重要,但目前利用爆炸技术改善低渗透油藏的效果还不够理想。分析认为主要原因是该技术的理论研究还不够完善,目前还存在不少问题急需深入研究,其中爆炸载荷作用下储层岩石的破坏规律就是一个较为重要的理论问题。为此,本文开展了爆炸激波对水泥试样损伤规律研究。本研究成果对于促进爆炸增产技术的发展具有重要理论意义和实用价值。本文首先提出了炸药距小水泥试样一定距离损伤的实验方案和炸药紧贴大水泥试样表面损伤的实验方案(图2-1和2-2),并设计了操作流程。测得水中激波波速为1500 ~1550m/s,并得到了激波在水中的衰减规律(式3-16),为小水泥试样的损伤实验奠定了基础。观测到了激波掠过后水泥试样中裂纹形貌的分布规律;分析了激波在水泥试样中的传播过程及裂纹的起裂扩展机理;推导了激波在水泥试样中的衰减规律(式3-21和3-33)。推导了激波压力与波速的关系,实现了激波压力的间接测量。研究发现损伤区的尺度与装药当量半径有较好的线性关系(式3-59和63)。在实验研究的基础上,用数值模拟的方法分析了激波在水和水泥试样中的传播过程及激波在界面上的反射和透射现象。计算了激波在水中的传播速度,且与实验结果一致。对比数值模拟分析结果和实验分析结果,发现二者吻合较好。最后对爆炸激波作用后水泥试样的损伤程度做了定量评价研究。建立了基于相对损伤度、裂缝孔隙度和裂缝渗透率等指标来定量评价水泥试样损伤程度的方法,并确定拉伸损伤区为主要评价区。测量了损伤评价所需要的参数,发现水泥试样的均匀性较好。研究发现激波峰值压力与动态抗拉强度之比是影响爆炸后水泥试样弹性波速的主要因素(式5-50);推导了环向拉伸应力与激波压力之间的规律(式5-68);研究了无量纲弹性波速、相对损伤度随无量纲环向拉伸应力之间的变化规律(式5-69和77);讨论了相对损伤度、裂缝渗透率和裂缝孔隙度之间的定量关系(式5-82和90)。推导了裂缝渗透率随无量纲环向拉伸应力的变化规律(式5-96),探索了使试样产生大量微裂纹并最大幅度提高渗透率的动载荷条件。更多还原

【Abstract】 Low permeability reservoir plays an increasing important role in petroleum exploitation with the development of petroleum industry, but the stimulation technology for low permeability reservoir by explosion method can not meet the demand for the development of petroleum industry. The main reason is that the theoretic research for the stimulation technology by explosion method is imperfect, and many theoretic problems should be deeply studied, and the rule of rock damage by exploding load is one of which should be essential studied. So the rule of cement sample damage by blast wave is studied in this thesis, and the rule acquired from which has theory sense and utility value to accelerate the development of the stimulation technology by explosion method.The cement damage experimental programs of explosive away from small cement sample and explosive hugging closely on big cement sample are proposed, and the operational scheme is also designed. The blast wave velocity in water is within 1500~1550 m/s, and the attenuation rule in water is also gained, which settle the bases for the experiment study of cement sample damage. The fracture distribution rule in the cement sample abaft blast wave by-passing is observed, and blast wave spreading process and the fracture initiation & propagation mechanism are analyzed. The attenuation rule of the blast wave in cement sample is deduced. The relationship between blast wave pressure and blast wave velocity is deduced, which can calculate the blast wave pressure indirectly. It is found that the damage zone dimension has a linear relationship with the explosive load equivalent radius.On the bases of experiment study, the blast wave spreading process and reflection & transmission effect on boundary between water and cement sample are analyzed by numerical simulation method. Blast wave velocity gained in water by numerical simulation is coincided with which gained in experiment. Comparing the result gained from the numerical simulation with which gained from experiment, it is found that they coincide with each other well.Quantitative evaluation for the cement sample damage after exploding is studied. Based on relative damage, fracture porosity and fracture permeability, the quantitative evaluation method for the cement sample after exploding is established, and the tensile damage zone is confirmed as the chief evaluation zone. The parameters need in the evaluation study is gained by experiment research, and it is found that the cement samples are high homogeneous. It is found that the ratio of maximum blast wave pressure and dynamic tensile strength is the main factor influence on elastic wave velocity of cement sample after exploding, and the relationship between the tensile stress in annular direction and blast wave pressure is also deduced. The rules between dimensionless elastic wave velocity, relative damage and dimensionless tensile pressure are obtained. The rules between relative damage, fracture permeability and fracture porosity are also gained. Using the result above-mentioned, the rule between fracture permeability and dimensionless tensile pressure is obtained, and the optimum dynamic load creating enough micro-fracture and enhancing the permeability greatly is studied.更多还原