Sedimentary Facies And Reservoir Characteristics Of Lower Es₁ In Liu62 Fault Block

Raoyang Sag is a secondary structural unit in the middle of the Jizhong Depression,Bohai Bay Basin,located in Suning County,Hebei Province.The study area is the Dawangzhuang-Liuxi fault structural belt in Raoyang Sag,Jizhong Depression,and the target interval is the lower member of the first interval of the Shahejie Formation（Es₁）.In the study area,the structure is complex and the sedimentary facies zone changes rapidly.The reservoir is dominated by low and medium porosity and permeability,and there is little difference in the resistivity between oil-water reservoirs.The oil-water accumulation is controlled by the three structure factors,lithology,and physical property,and the relationship between oil and water is complicated,so it is difficult to develop the oilfield reasonably.Based on the data of measuring,logging,analysis,core observation,oil test and production,and referring to previous geological research results,this paper uses the methods of combining macro and micro studies,qualitative analysis with quantitative calculation,geological and geophysical logging studies,and structural and sedimentary facies studies to finely divide and contrast strata and carry out sedimentary facies studies.Using core physical property analysis and other data,this paper studies the change rule of reservoir physical property,analyzes the correlation between sedimentary facies and oil and gas accumulation,establishes a reasonable lithology,physical property interpretation chart,and fluid property identification method,studies the law of oil and gas accumulation,and provides a basis for efficient oilfield development.The results showed that:（1）Under the control of marker beds,skeleton profiles,and sedimentary cycles,52 Wells were finely divided and compared,and the lower Es₁ was divided into two oil groups and 12 small beds.（2）The lithology of the lower Es₁ is mainly mudstone,siltstone,and fine sandstone,followed by a small amount of medium sandstone.The color is mainly gray and dark gray.The sedimentary structure is scour surface structure,cross-bedding,parallel bedding,and other sedimentary structures.（3）The main provenance direction of the lower Es₁ is northwest,and the provenance direction of some small beds is southeast and northeast.（4）The sedimentary sub-facies are delta front,and the main sedimentary microfacies types are distributary channel and sheet sand,followed by estuary bar and distal bar.（5）The thickness of individual sandstone is thin,and the distribution of sandstone is mainly controlled by sedimentary microfacies,which has an obvious controlling effect on the relative reservoir physical property.The distributary channel has good physical properties,but sheet sandstone and far bar have poor physical properties.The main porosity range is 10～15%,and a small part is 15～20%.The main permeability range is 1～10md,followed by 10～100md.（6）Fault is an important factor in controlling oil and gas accumulation,and lithology also plays an important role in oil and gas accumulation;The reservoirs with poor physical properties are oil-water,water-water,or dry reservoirs,which can form physical blocking in the high part of the structure.Oil sands in the area are small and scattered in distribution,which is controlled by many factors such as trap conditions,sedimentary facies,and physical properties.As a result of the action of multiple factors,a variety of oil-water aggregation modes have been formed,such as oil reservoir,water reservoir,oil-water mixed reservoir,and oil-bearing water reservoir.