石油学报 ›› 2012, Vol. 33 ›› Issue (1): 74-81.DOI: 10.7623/syxb201201009

• 地质勘探 • 上一篇    下一篇

地应力与断层封闭性之间的定量关系

王 珂 戴俊生   

  1. 中国石油大学地球科学与技术学院 山东青岛 266555
  • 收稿日期:2011-05-26 修回日期:2011-09-23 出版日期:2012-01-25 发布日期:2012-03-22
  • 通讯作者: 王 珂
  • 作者简介:王 珂,男,1987年7月生,2009年毕业于中国石油大学(华东),现为中国石油大学(华东)地球科学与技术学院在读博士研究生,主要从事储层地质及油藏描述研究。
  • 基金资助:

    国家重大科技专项“大型油气田及煤层气开发”(2011ZX05042-001)及“中西部前陆盆地构造地质、储层特征与有利区评价”(2011ZX05003-04)资助。

A quantitative relationship between the crustal stress and fault sealing ability

WANG Ke DAI Junsheng   

  • Received:2011-05-26 Revised:2011-09-23 Online:2012-01-25 Published:2012-03-22

摘要:

通过建立数学模型,推导出了三向地应力状态下断面正应力和剪应力的计算公式,并选取断层封闭系数、断层紧闭指数和断层剪切指数3个参数作为断层封闭性的定量评价指标。其中,断层封闭系数和断层紧闭指数越大,断层封闭性越强,而断层剪切指数与断层封闭性的关系与断层面所受正应力性质有关。当正应力为压应力时,断层剪切指数越大,断层封闭性越好;当正应力为张应力时,断层剪切指数越大则断层开启程度越高。最后分析了地应力大小和方向对断层封闭性的影响。结果表明,断层走向与最大水平主应力之间的夹角发生改变时,断面正应力和剪应力的变化趋势及其对断层封闭性的影响均是相反的。因此,在实际应用时,应对正应力和剪应力对断层封闭性的影响进行综合考虑。分析结果还表明,压性和压扭性断层的封闭性优于张性和张扭性断层的封闭性。饶阳凹陷中北部第三系构造应力场数值模拟及断层封闭性分析结果显示,沙二段和沙三段应为重点勘探层位,其次为沙一段和东营组。这与饶阳凹陷的勘探开发实际相一致。

关键词: 地应力, 断层封闭性, 定量评价参数, 构造应力场, 数值模拟, 饶阳凹陷

Abstract:

Calculation formula for normal stress and shear stress on fault plane in a triaxial crustal stress state were deduced through establishing mathematical models, and three parameters: fault sealing coefficient, fault tightness index and fault shearing index were taken as indexes to quantitatively evaluate the fault sealing ability. Analysis results demonstrate that the fault sealing ability shows better when the fault sealing coefficient and fault tightness index get greater, while the relationship between the fault shearing index and fault sealing ability is relevant to the property of normal stress that acts on fault plane. When normal stress is a compressive stress, the greater the fault shearing index, the better is the fault sealing ability, while the opening extent of faults gets greater with the increase of the fault shearing index when normal stress is an extensional stress. Moreover, the influence of the magnitude and direction of crustal stress on the fault sealing ability was analyzed. The result indicates that when the included angle between fault strike and the maximum horizontal principal stress changes, both the variation trend of normal stress and shearing stress on fault plane and its influence on the fault sealing ability are contrary, thus in practical application this influence should be synthetically considered. Furthermore, the fault sealing ability of compressive and compresso-shear faults is superior to that of extensional and tenso-shear faults. Numerical simulations of the Tertiary tectonic stress field and analysis of the fault sealing ability in the mid-northern Raoyang Depression demonstrated that the Sha-2 and Sha-3 members should be major targets of exploration, and the Sha-1 member and the Dongying Formation came next. This conclusion is consistent with the exploration and development practice in the Raoyang Depression.

Key words: crustal stress, fault sealing ability, quantitative evaluation parameter, tectonic stress field, numerical simulation, Raoyang Depression