鄂尔多斯盆地毛盖图地区盒8、山1段高含水致密砂岩沉积特征与分布规律

Sedimentary Characteristics and Distribution of Tight Sandstone with High Water Content in He 8 and Shan 1 Members, Maogaitu Area, Ordos Basin

通过岩心观察、测井曲线分析等技术手段,对鄂尔多斯盆地毛盖图地区盒8、山1段高含水致密砂岩沉积特征与分布规律开展研究,结果表明:(1)研究区岩石类型主要有泥岩、粉砂岩、细砂岩、中砂岩、粗砂岩、含砾粗砂岩和细砾岩等,砂岩成分成熟度中等偏好。(2)研究区沉积构造类型多样,多以河道特征为主,主要沉积构造有块状层理、粒序层理、平行层理、水平层理、板状交错层理、波纹层理、冲刷面。(3)研究区盒8段测井曲线形态有(齿化)箱形、钟形、齿化线形、叠置漏斗形,反映辫状河沉积环境;山1段测井曲线形态有箱形、钟形、齿形和指形,反映曲流河沉积环境。(4)盒8段为辫状河相,以发育辫状河道微相为主,河道成南北向展布,平面上不断交汇分叉,其中盒8下段河道和心滩微相最为发育;山1段、山2段为曲流河,河道非均质性变强,河网密度变稀;分流河道与河道间交互分布。

The sedimentary characteristics and distribution laws of the tight sandstone with high water cut in He 8 and Shan 1 members in Maogaitu area of Ordos Basin are studied by means of core observation and logging curve analysis.The results show that:(1) The rock types in this area mainly include mudstone, siltstone, fine sandstone, medium sandstone, coarse sandstone, pebbly coarse sandstone and fine conglomerate.The maturity of sandstone composition is medium.(2) There are various types of sedimentary structures in this area, mainly characterized by river channels.The main sedimentary structures include massive bedding, grain sequence bedding, parallel bedding, horizontal bedding, plate cross bedding, ripple bedding and scour surface.(3) The well logging curves of He 8 in the study area are(toothed) box-shaped, bell-shaped, toothed line-shaped and superposed funnel-shaped, reflecting the braided river sedimentary environment.The logging curves of Shan 1 member are box-shaped, bell-shaped, tooth-shaped and finger shaped, reflecting the sedimentary environment of meandering river.(4) The He 8 member is braided river facies, dominated by braided channel microfacies.The river channels are distributed in a north-south direction, with continuous intersection and bifurcation on the plane.The channel and central beach microfacies are most developed in the lower He 8 member.Shan 1 and Shan 2 members are meandering rivers with strong heterogeneity and sparse river network density.The distributary channel and interchannel facies are distributed alternately.These research results can provide technical support for the sustainable and stable production of tight sandstone gas reservoirs with high water cut in the western Sulige area, and has important reference value for the development of similar gas reservoirs.