甘泉地区长7段沉积岩特征与地质评价

Sedimentary rock characteristics and geological evaluation of Chang 7 member in Ganquan area

以甘泉区长7段为研究对象,应用岩心、薄片、粒度图像、X衍射等技术手段,结合钻、测井资料,对沉积岩特征进行定性和定量分析,并从区域实际情况出发,进行沉积岩地质评价。研究表明,长7段岩石以细粒砂岩为主,全段有机质类型为Ⅱ_(1)型、Ⅱ_(2)型,有机质成熟度适中,具有生烃能力;岩石组合类型有叠置砂岩型(薄厚均可见)、叠置砂夹薄层泥页岩型、泥页岩夹薄层砂岩型。平面上长7_(1)、长7_(2)细砂岩全区分布但差异明显,南部DG区最发育,长7_(3)黑色泥页岩区内厚度差异明显,西部LLY区厚度最厚,超过40 m。沉积物成因有三角洲前缘、湖泊、浊流、砂质碎屑流,形成的优势砂体连片分布、物性好、孔隙类型多样且数量多,与互层泥页岩形成近源储油和源内储油特征。

Taking Chang 7 member in Ganquan area as the research object,the characteristics of sedimentary rocks were qualitatively and quantitatively analyzed by core observation,thin section,particle analysis and X-ray diffraction experimental methods combined with drilling and logging data.The geological evaluation of sedimentary rocks was carried out according to the actual situation of the region.The results shows that the rocks of Chang 7 member are mainly fine-grained,and the organic matter types of the whole member areⅡ_(1) andⅡ_(2),with moderate maturity of organic matter and hydrocarbon-generating strength.The rock assemblages are superimposed sandstone type(visibly thin and think),superimposed sand clip thin layer shale type and shale thin layer sandstone type.On the plane,the distribution of Chang7_(1) and Chang7_(2) fine sandstone is obvious,the southern DG area is the most developed,the thickness difference of Chang7_(3) black shale area is obvious,and the thickness of western LLY area is more than 40 m.The factors of sediments are deltaic front,lake,turbid current and sandy clastic flow.The dominant sand bodies are contiguously distributed with good physical properties,various pore types and have a large number of pores,presenting the characteristics of near source oil storage and source oil storage with interbedded shale.