构造裂缝多参数定量计算模型

Multi-parameter quantitative calculation model for tectonic fracture

以裂缝在古应力场中产生、在现今应力场被改造为研究路线,以应变能、表面能理论为基础,选用库伦-莫尔准则及格里菲斯准则分别作为岩石剪性及张性破裂判据,建立造缝期古应力场及现今应力场三向挤压应力状态及有张应力存在情况下裂缝参数计算模型,并用此模型进行实例分析计算。结果表明:现今应力场中难以产生裂缝,裂缝体积密度、线密度与古裂缝相同,现今裂缝开度及渗流性能受作用在裂缝面上的正应力及剪应力影响,相比古裂缝参数有明显变化;石港油田阜二段断层附近为储层裂缝发育密集区,裂缝开度、孔隙度及渗透率等参数高值区主要位于靠近断层的构造高部位。

Tectonic fracture occurred in palaeostress field and was modified in current stress field. The calculation model of fracture parameter in fracture building stage, palaeostress field and current stress field in triaxial compression state and exten- sion stage, was developed based on strain energy and surface energy theory. The Coulumb-Mohr principle was applied to examination of shear fracture, while Griffith principle was applied to examination of tension fracture. The results show that the rocks hardly burst in current stress field. The volume density and linear density of current fracture are same with those of palaeofracture, while the aperture and seepage of fracture change significantly. The current fracture parameters are affected by positive stress and shear stress on the fracture surface. The Fuer segment reservoir fractures in Shigang Oilfield mainly distribute near the faults. The high value area of aperture, porosity and permeability of fractures is in the structural high situs near the faults.