| 井底压力对岩石破碎的影响机制及应用研究 |
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| 引用本文： | 郑德帅,冯江鹏.井底压力对岩石破碎的影响机制及应用研究[J].岩土力学,2011,32(Z1):205-208. |
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| 作者姓名： | 郑德帅 冯江鹏 |
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| 作者单位： | 1. 中国石化石油工程技术研究院，北京 100101；2. 中国石油大学石油工程教育部重点实验室，北京 102249 |
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| 基金项目： | 973课题“深井复杂地层破岩机理与高效破岩方法”(No.2010CB226703) |
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| 摘 要： | 钻井液井底压力与地层孔隙压力是影响岩石破碎的重要因素，由于岩石具有一定的渗透率，在压力差的作用下钻井流体与地层流体之间会相互影响，导致靠近井底的地层孔隙压力发生变化。实际的地层孔隙压力随时间与距离变化的规律可以使用一维不稳定渗流模型来描述和计算。在此分析基础上，综合分析地应力、井底压力及钻头牙齿吃入地层产生的应力，计算出任意平面上所受的剪应力和正应力，然后使用摩尔–库仑准则来判定岩石的破坏。建立这样一个综合各种因素的井底岩石破碎模型，可以将各种因素尤其是实际井底压力差的作用清楚地表达出来。该模型可以较好地解释欠平衡钻井提高钻速的力学机制，并为随钻地层孔隙压力监测dc指数法的适用范围提供明确的计算方法
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| 关 键 词： | 压差 岩石破碎 地层孔隙压力 欠平衡钻井 dc指数 |
| 收稿时间： | 2010-09-21 |
Mechanism of effect of downhole pressures on rock failure and its applications |
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| ZHENG De-shuai,FENG Jiang-peng.Mechanism of effect of downhole pressures on rock failure and its applications[J].Rock and Soil Mechanics,2011,32(Z1):205-208. |
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| Authors: | ZHENG De-shuai FENG Jiang-peng |
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| Institution: | 1. Sino-Pec Research Institute of Petroleum Engineering, Beijing 100101, China; 2. MOE Key Lab of Petroleum Engineering, China University of Petroleum, Beijing 102249, China |
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| Abstract: | The differential pressure between mud pressure at bottom hole and pore pressure in formation influences the rate of penetration(ROP) when drilling oil and gas wells; but its mechanism is not clear. The pore pressure near the well bore bottom is not the original pore pressure; and it is related with location and time. This paper uses one dimension unstable seep model to describe and calculate the law of actual pore pressure under various times and locations. The shear stress and normal stress at any plan can be calculated based on crustal stress, bottom pressure, pore pressure and the stress caused by insert invasion. Using the Mohr-Coulomb model to judge the rock failure and get the invasion depth expression. Because the invasion depth of bit tooth is closed with ROP; with that expression the effect mechanism of differential pressure on ROP is studied and explained explicitly. The mechanism can be applied to some fields, such as getting higher ROP in under-balance drilling and providing an explicit parameter to calculate the suitable condition for dc index method |
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| Keywords: | differential pressure rock failure pore pressure under-balance drilling dc index method |
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