一种新的断裂破坏泥岩盖层程度的综合研究方法

为了研究含油气盆地断裂发育区断裂对盖层的破坏及对油气分布的影响,在前人研究的基础上,通过定义断裂综合封闭能力和泥岩盖层综合封闭能力,并计算两者比值,得到断裂对泥岩盖层综合破坏程度的计算方法。通过此计算方法建立了一套新的断裂对泥岩盖层综合破坏程度的研究方法,并将此方法应用于海拉尔盆地贝尔凹陷贝西斜坡呼和诺仁构造F5断裂对大一段泥岩盖层综合破坏程度的研究。结果表明:F5断裂对大一段泥岩盖层综合破坏程度在测点4、6、9、10、11处为较强—强级别,其他测点处均为较弱级别;在盖层受破坏程度较强的测点4、6、9、10、11附近,钻井的含油性为油气显示和无显示,其原因是盖层所受断裂综合破坏程度较大,油气保存程度较低;在盖层受破坏程度较弱的测点1—3、5、7—8、12—15附近,盖层所受断裂综合破坏程度较小,油气保存程度较高,井的含油性为工业油流和低产油流。F5断裂对大一段泥岩盖层的综合破坏程度评价结果与南二段油气显示关系相符,证明此方法用于断裂对泥岩盖层综合破坏程度研究是可行的。

A New Predicting Method for Comprehensive Damage Degree of Mudstone Caprock by Fault and Its Application

In order to study the damage degree of fractures to caprock and its influence on oil and gas distribution in a fault developed zone in a petroliferous basin,based on the previous studies,we defined the comprehensive sealing ability of fractures and the comprehensive sealing capacity of mudstone caprock,and calculated the ratio of these two,and finally obtained the method for calculating the comprehensive damage degree of fractured mudstone caprock.This method was applied to calculate the comprehensive damage degree of K1d1 mudstone caprock in Huhenuoren structure in Bessie slope of Baer sag Hailar basin.The results show that the comprehensive damage degree of the F5 fault to K1d1 mudstone caprock is in the level of strong-stronger at the measuring site of No.4,6,9,10 and 11,but in weak level at the other measuring sites.In the site of No.4,6,9,10 and 11 of the caprock with strong damage degree,no or little gas and oil appear in drilling well.The preservation of oil and gas is poor for the reason of strong caprock damage caused by fractures.In the measuring site of No.1-3,5,7,8 and 12-15 of the caprock with weak damage degree,the preservation of oil and gas is relatively better,and the near oil-bearing properties of well are industrial oil well or low production well.The comprehensive damage degree of F5 fault to K1d1 mudstone caprock is consistent with the K1n2 oil and gas show.It is proved that the method is feasible for study on the comprehensive damage extent of mudstone caprock by fault.