高陡构造易漏地层钻前裂缝定量描述方法

Pre-spud quantitative description method for fracture in thief formation of steeply-folded structure

高陡构造地质条件复杂且裂缝发育,钻井过程中容易发生漏失,因此,需要对高陡构造地层进行钻前裂缝定量描述,以便有效预测漏失层位,制定准确的防漏堵漏措施。文中提出了一种能够定量描述高陡构造易漏地层构造裂缝的新方法。该方法从整体地质构造入手,结合区域构造宏观地质力学特征与微观岩石力学机理,基于所建立的区域地质构造模型,确定地质构造的整体力学性能、加载历史和过程、力学边界条件及岩石力学参数,计算地质模型各单元的地应力分布;基于断裂及损伤力学理论,判断裂缝发育区及裂缝,获取其构造裂缝的分布规律,得出构造裂缝的开度、孔隙度、渗透率及线密度等参数,从而为钻前漏失定量预测及堵漏材料类型及尺寸选择提供理论依据。

The geology condition of steeply-folded structure is complex,tectonic fractures develop and lost circulation happens usually during drilling,which brings great harm to safe drilling.Therefore,it is important to describe the tectonic fracture properties in order to predict effectively the thief formation and make measures of preventing lost circulation or bridging fractures.The paper presents a new approach which can carry out the pre-spud quantitative description of tectonic fracture in thief form ation of steeplyfolded structure.From the geological structure of the whole,combined with block macroeconomic mechanical characteristics and microscopic rock mechanism,and based on the geological structure model,the whole mechanical properties,loading history and condition,mechanical boundary condition and rock mechanics parameters are determined using this approach.The in-situ stress distribution of geological model for the units is calculated.Based on fracture mechanics and damage mechanics theory,the fracture development zone and fracture are judged and the structural fracture distribution is determined,obtaining the parameters such as structure fracture opening,porosity,permeability and fracture density,which can provide theory basis for the quantitative prediction of pre-spud loss and the selection of lost circulation material type and size.