有限元数值模拟方法在构造裂缝预测中的应用

Application of the finite element numerical simulation method in fracture prediction.

对地下油气储层的裂缝预测是中外油气勘探和开发领域的技术难题。尽管目前有多种方法可以对地下裂缝的分布状况进行预测,但都存在不少问题。为此,提出采用有限元数值模拟方法对构造裂缝的发育状况进行预测。该方法首先是在地质规律指导下建立客观的油藏构造精细地质模型;然后将岩石力学实验与有限元数值模拟方法相结合,并将由声发射实验测算的古构造应力值,作为应力场模拟的绝对反演标准;最后模拟裂缝主要形成期的古构造应力场,依据对应力场的分析预测储层构造裂缝的发育程度。模拟结果表明,有限元数值模拟方法不仅能够恢复构造裂缝形成期储层构造应力场的分布,而且可以依据地质力学理论对储层构造裂缝的分布及发育程度进行预测,为裂缝性油藏的勘探和开发提供了技术支持。

The fracture prediction of reservoirs is a worldwide problem in the exploration and development of hydrocarbon.There are many prediction methods for the fracture distribution,but each has cer- tain defects.So the author put forward the method of finite ele- ment numerical simulation to predict the distribution of subsur- face tectoclases.The following researches are made:1)a fine ob- jective structural model of reservoir should be constructed under geological rules;2)rock mechanical experiment and finite ele- ment numerical simulation should be integrated and the palaeo- tectonic stress from the acoustic emission test should be treated as an absolute constraint condition for the stress field simulation; 3)the palaeotectonic stress field of the stage with fractures mainly generated is simulated,then the development level of fractures is predicted according to the results above.The simula- tion results indicate that the method of finite element numerical simulation can not only reconstruct the tectonic stress field of fractures generating stage,but also predict the tectoclases distri- bution and development level quantitatively based on the theory of geomechanics.So this method can supply a technical assis- tance for the hydrocarbon exploration and development in frac- tured reservoir.