摘要
轮南地区三叠纪时由于受轮台断裂影响，断裂两侧地形高差大，冲积扇沉积直接进入湖盆，形成扇三角洲沉积体群。扇三角洲沉积体明显地可划分为：扇三角洲平原亚相、扇三角洲前缘亚相和前扇三角洲亚相。扇三角洲前缘亚相中的水下分流河道沉积砂体是主要的油气储集体，储集砂体最发育地区位于桑塔木断垒带及以南地区。储集砂岩类型主要是矿物和结构成熟度较低的细─粗粒岩屑砂岩，石英含量１５～６０％，长石含量１０～２５％，岩屑含量３５～７５％。储集层的储集空间以次生溶蚀孔为主，其中包括粒间溶孔、粒内溶孔、超大孔隙、胶结物溶蚀孔、微孔隙，其次是原生孔和裂缝。轮南地区三叠系属深埋、高孔、高溶储层特征，埋深４２００～５４００ｍ，其储集砂体，泥质含量低，小于５％。有机酸和无机酸对颗粒的溶蚀，扩大了储集空间，粘土矿物中绝大部分为斑点状高岭石，不易堵塞孔隙和喉道，低的地温梯度和短期的深埋等使三叠系储层具备高孔高渗的特点。孔隙度为１５～２８．５４％，渗透率为１０～４３１７．９×１０－３ｕｍ２。
Being influenced by Landei Fracture of Triassic in Lunnan area, the elevations in the both sides on the fracture are large enough to make the alluvial fan to enter directly the lacustrine basin and to form the tan delta group deposition.The fan deltaic body can be divided into three subfacies,named fan delta plain,fan delta front and pro-fan delta.Subaquous distributary channel sand bodies in the fan delta front are most important reservoir of oil and gas. The developing area of reseroir is located at SangTamu Horse Belt and the southern port.The kinds of reseroir rock are mainly fine-coarse grained lithic sandstone with lower maturity of the mineral and texture,containning quarts 15～60%,feldspar 10～25 %,rockclast 35～75%The most important reservoir space is secondary solution pore, including intergranular solution pore, intraparticalar solution pore, oversize pore, cement - dissolved pore, secondly micro - pore,primary pore and fissures.The Triassic reservoir are characterized by deep burial, high porosity and good permeability,burial depth 4200～5400m,peosity of 15～28. 45%,permeability of 10～4317' 9 × 10-3um2.Finally the origin of high porosity and good permeability of Triassic reservoir is discussed under such a baital depthi:1. Coarse grain reservoir sediments; 2. Usually less than 5% of clay content; 3. With thick mudstone (12～175m)between sandbeds ; 4. Increasing reservoir space because of the clastic grain dissolved by organic and inorganic acids ; 5. Most kaolinite is of porphyritic texture,so it is not easy for them to fill the pore and throat; 6. Lower geothermal gradient and deep burial in high speed and short period, etc.
出处
《沉积学报》
CAS
CSCD
北大核心
1994年第2期54-62,共9页
Acta Sedimentologica Sinica
