采用定面射孔时射孔参数的优选方法

HOW TO DECIDE OPTIMUM PERFORATION PARAMETERS FOR COPLANAR PERFORATION

采用定面射孔技术可降低页岩储层破裂压力,有效改善近井筒裂缝复杂形态,定面射孔参数设计是决定岩石破裂的关键。通过有限元方法建立页岩储层的数值模型,对定面射孔参数进行单因素分析,得出不同射孔参数组合方式影响破裂压力的规律。结果表明,破裂压力随射孔密度的增加呈非线性降低,随射孔孔径增加大幅度下降,而与射孔深度变化无相关性。优化得出最优射孔参数组合方式为孔密21孔/m、孔径0.03 m、孔深0.52m。采用灰色关联度分析法,对定面射孔参数进行多因素分析,评价上述射孔参数组合的优劣性,发现射孔参数组合的破裂压力值与其关联度呈负相关性,并且射孔参数组合(孔密12孔/m、孔径0.03 m、孔深0.52 m)为最优射孔参数。开展室内真三轴物模实验对比分析储层破裂压力,进一步验证了灰色关联度分析方法的可靠性。

The coplanar perforation technology can reduce the fracture pressure of shale and the complexity of near-wellbore fractures. The coplanar perforation parameter design is the key to rock breakdown. A numerical model for shale reservoir was established using finite element method to do single factor analysis on coplanar perforation parameters and so to find the laws governing the effects of different perforation parameter combinations on the fracture pressures. The results showed that the fracturing pressure decreased nonlinearly with the increase of perforation density,decreased rapidly with the increase in shot diameter,and had no relation with the shot length. The optimal perforation parameter combination was decided as shot density 21holes/m,shot diameter 0. 03 m and shot length 0. 52 m. Then multiple factor analysis was made on the coplanar perforation parameters with grey correlation analysis to evaluate the pros and cons of the perforation parameter combination. it showed the negative correlation between the fracture pressure and correlation degree of the perforation parameter combinationn and the perforation parameter combination of shot density 12 holes/m,shot diameter 0. 03 m and shot length 0. 52 m was the most close to the optimal perforation parameter combination. A large-scale real tri-axial hydraulic fracturing simulation experiment later conducted further proved that the grey correlation analysis was reliable.