A Study On Formation Mechanisim And Main Controlling Factors Of The Heavy Oil Reservoirs In Liaodong Bay Area

Liaodong Bay Depression have abundant heavy oil resource which is located in the northeastern region of the Bohai Bay Basin,it is the cenozoic basin developed under the strike-slip faults background.However,the origin,viscosify process and Main controlling factors of heavy oil are not clear.This paper studied on the basic characteristics,the area of heavy oil genesis and heavy oil accumulation controlling factors,then divided the levels of the degradation of heavy oil,and finally,established the heavy oil reservoir accumulation model.We studied the relative density,viscosity,sulfur content,wax content and other characteristics and distribution of crude oil by using physical property data of heavy oil in the study area,and found that the heavy oil in Liaodong Bay area is mainly affected by the biodegradation of crude oil,it has the characteristics of high density,high viscosity,high acidity,high adhesive quality,high asphaltene content,low sulfur content and low wax content.Based on the study of the biomarkers in the study area,the degradation level of heavy oil was divided into 9 grades,in the study area,the distribution of crude oil degradation is 1-7,there isn't 8 and above grade.The grading standards is only for this region,so it is more targeted,so that the different structures in different regions of the heavy oil degradation situation at a glance.We found the heavy oil are mainly distributed in the middle and southern part in Liaodong Bay area,the heavy oil degradation degree is high in LD5-2N,LD6-1,SZ36-1 structure,the area whose normal oil and heavy oil are coexist,such as JX1-1 structure,the heavy oil degradation level decreased with the increase of buried depth.Based on the analysis of the characteristics of crude oil and formation water in the study area,the heavy oil in this area is mainly produced by biodegradation,and the formation of water by fault is the precondition for the thickening of the oil,the factors affecting the thickening of the oil reservoir are the buried depth,migration distance and poor storage conditions.According to the difference of Liaodong Bay area heavy oil reservoir controlling factors of hydrocarbon accumulation and the causes,we divided them into two kinds reservoirs.One is the heavy oil reservoir of edge accumulation side viscosify,the reservoirs are mainly distributed in Liaoxi low uplift,it is the two-way supply source from between Liaoxi and Liaozhong sag,and mainly from Liaozhong sag,the migration distance is long,the oil and gas began viscosify during migration,When the reservoir is formed in the trap,the oil is further viscosify due to the poor conditions of the seal rock.The other one is that viscosify process of crude oil happen after the accumulation,In the process of hydrocarbon accumulation,the migration distance is relatively small,and it is gathered nearby.The fault plays a decisive role in the formation of the heavy oil reservoir and the viscosify of the oil.