液相放电等离子体破岩机理与破岩规律研究

The rock in deep formation has a high degree of hardness and abrasiveness. One of the key problems which the development of deep oil and gas resource faced with is how to improve rock-breaking efficiency in deep and ultra-deep well. Electrohydraulic plasma fragmentation method is a kind of new rock-breaking method which can convert electrical energy into mechanical energy efficiently, but at present scholars at home and abroad had little research on its rock-breaking mechanism and rules. This project will use laboratory experiments, theoretical analysis and numerical simulation methods to give a deep research on electrical characteristics of high voltage pulsed discharge in liquid, electrohydraulic plama water shock wave propagation characteristics, rock damage characteristics under water shock wave load and the rock-breaking rules of electro-hydraulic disintegration method. Through this study, this project will establish the mechanical models for water shock wave pressure attenuation and rock damage and reveal general rock-breaking mechanism of this method. The influence law which electric parameters(voltage, frequency, length between electrodes, shape of electrode, etc.), rock mechanics(hardness, abrasiveness, etc.) and properties of drilling liquid affect the efficiency of rock disintegration process will be discussed. Finally we will put forward the rock breaking theory and method of electrohydraulic plasma fragmentation method. This research result has great significance for the improvement of deep and ultra-deep well rock-breaking efficiency and quick exploration and development of deep oil and gas resources.

深部地层岩石硬度高、研磨性强，如何提高深井、超深井破岩效率是深层油气资源高效开发面临的关键问题之一。液相放电等离子体破岩方法是一种将电能转换为机械能的新型高效破岩方法，目前国内外学者对其破岩机理与破岩规律研究甚少。本项目拟综合运用室内实验、理论分析和数值模拟等方法，着重进行液相高压脉冲放电的电学特性仿真、液相放电水激波的压力传播特性分析、冲击载荷作用下岩石动态损伤特性以及液相放电等离子体破岩规律研究，为提高硬地层、超硬地层破岩效率奠定理论基础。通过本项研究，建立液相放电水激波压力衰减模型和水激波载荷下岩石动态损伤模型，揭示液相放电等离子体破岩机理，探讨放电参数（电压、频率、电极间距、电极形状等）、岩石特性（硬度、研磨性等）以及钻井液性能等因素对破岩效果的影响规律，最终形成液相放电等离子体破岩理论与方法。该研究成果对于提高深井、超深井破岩效率，加快深层油气资源勘探开发具有重要意义。

随着我国中浅层油气探明储量增长越来越缓慢，目前油气勘探开发的重点逐步由中浅层转向深层。深部地层岩石硬度高、研磨性强，如何提高深井、超深井破岩效率是深层油气资源高效开发面临的关键问题之一。本项目提出利用液相放电等离子体技术来提高破岩效率，并围绕液相高压脉冲放电的电学特性仿真、水激波压力特性研究及岩石损伤模型、液相放电等离子体破岩室内实验进行了深入的研究及分析。取得的主要成果如下：.（1）基于脉冲功率技术，对液相高压脉冲放电的电学特性仿真分析，利用仿真软件Multisim对高压脉冲电路进行了模拟，得到了主要放电参数随电路元件参数的变化规律，为高压脉冲发生器的制备提供了最佳电路参数组合。.（2）基于基尔霍夫方程、能量守恒方程、声波近似方程，对高压脉冲放电物理过程进行了深入研究，分析了等离子体通道形成和膨胀的微观机理，解释了水激波形成原因，并建立了液相放电水激波的压力衰减模型。.（3）基于冲击动力学，研究了水激波动载荷作用下岩石的损伤机理，并建立了岩石损伤模型，利用ANSYS/LS-DYNA模拟水激波破岩过程，通过室内实验验证了模型的准确性后进行参数分析。.（4）利用液相高压脉冲放电的电学特性仿真结果和破岩过程的特点，设计了液相放电等离子体电路和反应器，并考虑电压、电流和激波压力测量需求，设计了数据测量系统。.（5）通过改变实验电路的放电参数、岩石类型和岩石力学特性、液体的电导率，研究了不同实验条件下液相放电等离子体破岩效果的影响规律。并基于上述研究成果，解释了液相放电等离子体破岩过程和作用机理，提出了液相放电等离子体破岩理论与方法。.该研究成果对于提高深井、超深井破岩效率，加快深层油气资源勘探开发具有重要意义。