鄂尔多斯盆地吴起—定边地区长8沉积相

Sedimentary facies of Chang 8 oil bearing formation in Wuqi-Dingbian area,Ordos Basin

目的探究鄂尔多斯盆地吴起—定边地区长8油层组沉积相类型及发育规律。方法以岩心观察的岩石相标志及测井相分析为基础,通过井剖面的相序分析、联井沉积相对比剖面及砂地比值分布规律进行综合研究。结果确定了吴起—定边地区长8油层组的沉积相类型、发育特征及沉积相展布规律。结论吴起—定边地区长8油层组发育西北、东北及西南3个方向的浅水台地型三角洲前缘沉积,其中西北和东北两个方向的三角洲前缘沉积占主导地位,不同方向三角洲前缘水下分流河道的分布具"沿河口带变宽并叠置连片"的规律。

Aim To establish sedimentary facies types and development regulations of Chang 8 oil-bearing formation in Wuqi-Dingbian area,Ordos Basin.Methods On basis of petrofacies characteristics of drill cores and analysis of well logging electrofacies,it is studied by means of synthesized analysis of facies sequence of well profiles,comparison profile of joint well sedimentary facies and distribution regulations of sandy land ratio.Results Sedimentary facies types,characteristics and distributary regulations of sedimentary facies are confirmed.Conclusion Chang 8 oil-bearing formation in Wuqi-Dingbian area develops frontal deposition of shallow water terrace type deltas,which were sourced from northwest,northeast and southwest,of which deltas frontal depositions of northwest and northeast sources are dominated.Distributions of subaqueous distributary channels of deltas front in different directions have the characteristics of becoming width and sheet like overiding along river mouth.