泥岩盖层排替压力特征及其影响因素——以三水盆地古近系布三段为例  

Displacement pressure features of mudstone caprock and its influencing factors:A case of the 3rd Member of Buxin Formation of Paleogene in Sanshui Basin

作　　者：唐鑫萍 TANG Xinping(Exploration and Development Research Institute of PetroChina Dagang Oilfield Company,Tianjin 300280,China)

机构地区：[1]中国石油大港油田分公司勘探开发研究院,天津市300280

出　　处：《录井工程》2021年第2期122-129,共8页Mud Logging Engineering

基　　金：中国石油天然气集团科技专项“成熟探区精细勘探关键技术”(编号:2019D-0707)。

摘　　要：三水盆地古近系布三段泥岩盖层埋藏较浅,介于600~1800 m之间,下伏油气藏具有一定的逸散风险,盖层封闭性对于该区油气勘探研究至关重要。通过开展布三段泥岩排替压力实验测试,结合X射线衍射、扫描电镜等岩石矿物分析手段,开展排替压力特征及其影响因素研究,取得了以下结果(1)布三段泥岩排替压力介于6.67~16.36 MPa之间,平均值11.83 MPa,总体呈现Ⅰ-Ⅱ类盖层特征,与其他地区的泥岩盖层排替压力相比,具有“较浅埋深、较高排替压力”的特点;(2)本区泥岩盖层排替压力随埋深有一定增加趋势,但相关性较弱,结合前人盆地演化研究分析表明,布三段泥岩具有“现今浅埋、曾经深埋”的特点,据剥蚀厚度推测样品古埋深为1800~3000 m,该埋深区间内岩石已较致密,排替压力受深度影响不显著;(3)泥岩盖层排替压力与黏土矿物含量成正比,且相关性好,布三段泥岩黏土矿物以伊利石为主、其次为高岭石与伊蒙混层,该黏土矿物组合类型吸水膨胀性较好,有利于提高泥岩盖层排替压力。综合分析表明,研究区有利盖层分布应当重点考虑黏土矿物含量、矿物组合吸水膨胀性2个因素。该研究突破了以往“泥岩埋藏越深、排替压力越大”的笼统认识,可为该区有利盖层条件预测和其他地区泥岩盖层研究提供参考。The mudstone caprock of the 3rd Member of Buxin Formation of Paleogene in Sanshui Basin buries shallowly between 600~1800 m.With a certain risk of escape in the underlying oil and gas reservoirs,the sealing of caprock is crucial in the hydrocarbon exploration in this area.By experimental tests on displacement pressure of mudstone in the 3rd Member of Buxin Formation,research on displacement pressure features and the influencing factors is conducted combined with X-ray diffraction,SEM and other rock and mineral analysis methods.Results achieved are as follows.First,The displacement pressure of sandstone in the 3rd Member of Buxin Formation is between 6.67~16.36 MPa with an average of 11.83 MPa,overall signifying typeⅠ-typeⅡof cap layer indications.Compared with the one elsewhere,it is low in burial depth and high in displacement pressure.Secondly,The displacement pressure of mudstone caprock in this area tends to increase with burial depth in a low correlation.Based on the previous studies of basin evolution,the analysis indicates that the mudstone in the 3rd Member of Buxin Formation is shallowly buried now and deeply once.According to the denudation thickness,it is inferred that the ancient burial depth of the sample is 1800~3000 m,in which the rocks are compact and the displacement pressure is not significantly affected by the depth.Thirdly,displacement pressure of mudstone caprock is well proportional to clay mineral content.The clay mineral combination of the mudstone in the 3rd Member of Buxin Formation is mainly illite,followed by kaolinite and illite/smectite formation,Asorbent and swellable,it helps to increase displacement pressure of mudstone caprock.Comprehensive analysis indicates that on the distribution of favorable caprocks,two factors should be highlighted in the study area,clay mineral content,and water absorption and swelling of mineral combination.This research breaks through the previous understanding that the deeper mudstone is buried,the greater the displacement pressure is.It provides r

关 键 词：泥岩盖层 排替压力 黏土矿物 封闭性 古近系布心组 三水盆地 

分 类 号：TE132.1[石油与天然气工程—油气勘探]