渤南油田沙三段沉积相和储层研究

A STUDY OF THE SEDIMENTARY PHASES AND THE RESERVOIR ROCKS IN Sa Ⅲ FORMATION IN BONAN OIL FIELD

渤南油田沙三段是油田的主要含油层系。通过取心井、岩屑录井及测井资料,研究了岩石的岩性序列、粒度演变、结构构造等,论证了渤南油田沙三段浊积扇沉积。并将各沉积时间单元的浊积砂体分为内扇、中扇、外扇亚相及内扇补给河道、阶地、天然堤及中扇辫状河道、叶状体等微相。文中阐述了各亚、微相砂体的储层特点,从储层的粒度、渗透率及微观孔喉结构的变化,分析其对各相带储油性质的影响,中扇储油性能较好,其叶状体部位岩性较均一,是储油的最佳场所,多数高产油井分布于该相带中。

The third member of shahejie formation in Bonan oilfield is a typical turbidites. It is the major oil-bearing beds in this oilfield. Based on an investigation on abundant data from cores and cuttings as well as geo-physical logging, and a study of the lithological sequence、the evolution of the grain-size, the distribution and the textures and the structrues of the rocks…etc, this paper demonstrates that the depositional phases of the third member of shahejie formation belongs to a turbidite fan, and the sediments were come from the Gudao uplift on the E-S direction of the studied area. According to the sedimentary facies analysis, the turbidite sand body is consisted of the subfacies including inner-fan, middle-fan and out-fan as well as the microfacies including feeder cha-nnel, terraces and natural levels of inner-fan, braided channel and lobe of middle-fan. There are differences between the pore structures and reservoir properties in these oil-bearing sand bodies resulted from the difference of the microfacies and the depths. This paper also demonstrates the reservoir’s characters of each subfacies and microfa cies, and analysis the grain-size, the permeability and the changes of the porosity and their effects on the characteristics of reservoirs. The middlefan sediments, especially the lobe, is the best one with regard to the oil-bearing features because they are uniforme in lithology and are well sorted. Many high-yield oil wells are located in this type of reservoir rock.