大牛地气田马五_(1+2)亚段风化壳储层地质甜点预测  

Predicting geological sweetspots in Ma 5^(1+2 )submember of weathered crust reservoirs,Daniudi gasield,Ordos Basin

作　　者：刘嘉[1] LIU Jia(Sinopec North China Oil&Gas Company,Zhengzhou,Henan 450006,China)

机构地区：[1]中国石化华北油气分公司,河南郑州450006

出　　处：《天然气技术与经济》2025年第1期27-36,共10页Natural Gas Technology and Economy

摘　　要：鄂尔多斯盆地大牛地气田奥陶系马家沟组五段整体处于海退期,纵向分为10个亚段,马五_(1+2)亚段处于相对海退期,受淡水淋滤、岩溶作用影响,形成大量的溶蚀孔、洞、缝,主要发育灰色白云岩夹少量石灰岩,是油气储集的重要场所。为了预测该气田马五_(1+2)亚段地质甜点区,以钻穿目的层580余口井为研究对象,分析了岩心、测井、录井资料,指出了目的层发育灰云坪、云坪、云灰坪、泥云坪共4种沉积微相,结合古地貌特征,刻画该气田马五_(1+2)亚段储层厚度平面分布,参考气井生产动态资料,预测优质储层分布范围,圈定地质甜点。研究结果表明:①马五_(1+2)亚段纵向发育7期沉积旋回,地层自下而上,泥质含量增多,反映了水体变浅、含盐度减小的趋势;剖面由北向南,泥质含量减小,反映了水体加深、含盐度增加的趋势。②马五_(1+2)亚段储层整体向西增厚,南北向厚度差异明显,最大相差24m,东西向变化平缓,最大相差8m,划分出岩溶台丘、残丘、斜坡、高地、洼地、沟槽共6个地貌单元,储层主要位于岩溶台丘、残丘部位。结论认为:①优质储层主要位于灰云坪、云坪部位,残留储层厚度大,白云岩含量占比高,分布范围自北东向南西扩大,台丘、残丘部位的厚度普遍超过4m,斜坡部位厚度介于2~6m;②优选的3个地质甜点区均建立于优势微相、优势岩相和优势古地貌单元之上,优质储层厚度超过4m,孔隙度超过2.5%,成像测井显示裂缝、溶蚀孔洞发育,储层物性好,含气饱和度超过15%,气测全烃含量超过20%,通过单井验证,累计产气量超过2000×104m3,可以作为水平井井位高效部署的参考区域。The fifth member of the Ordovician Majiagou Formation(Ma 5 Member)in Daniudi gasfield is standing in re-gression.Vertically,it is divided into 10 submembers(Ma 51 to Ma 510),among which Ma 5^(1+2) is still in relative regression.Numerous dissolved pores,vugs and fractures induced from fresh water leaching and karstification are extended into Ma 5^(1+2) where gray dolomite is dominantly developed with a little limestone to accumulate hydrocarbon.Therefore,cores,well-and mud-logging data from over 580 wells drilling through the target were analyzed to predict geological sweetspots of Ma 5^(1+2) in this field.And that there developed 4 types of sedimentary microfacies,including calcareous dolomite flat,dolomite flat,dolomitic limestone flat,and argillaceous dolomite flat,was pointed out.Furthermore,combined with paleogeomorpho-logical natures,the thickness distribution of Ma 5^(1+2) reservoirs on the plane was characterized.By referring to production data of gas wells,the extension of quality reservoirs was predicted,and the sweetspots were delineated.Results show that(i)7 episodes of sedimentary cycle are developed vertically in Ma 5^(1+2) where shale content increases from below,meaning the decreasing trend of waterbody depth and salinity while this content decreases from north to south on profile,implying the increasing trend of waterbody depth and salinity;and(ii)Ma 5^(1+2) reservoirs overall get thicker to the west,and their thickness varies greatly along north to south,with the maximum thickness difference of 24 m,but gently along east to west,with the maximum difference of 8 m.Six geomorphological units are identified,i.e.,karst platform mound,monadnock,slope,highland,low-lying land and trough,and the reservoirs are mainly located in the first two units.In conclusion,the quality reservoirs are mainly deposited in both calcareous dolomite flat and dolomite flat.Rich in dolomite extended from northeast to southwest,the residual reservoirs are thick.This thickness often exceeds 4 m in both platform mound and mo-

关 键 词：鄂尔多斯盆地 大牛地气田 马五1+2亚段 岩溶储层 地质甜点 

分 类 号：TE37[石油与天然气工程—油气田开发工程] P618.13[天文地球—矿床学]