Evaluation Of Exploration Targets For The Mesozoic Reservoir In Zaoyuan Oilfield

After 30 years development of Zaoyuan Oilfield,the number of newly discovered structural reservoirs in the middle-shallow layer is decreasing day by day,oil and gas exploration have to expand to the deep zone or special lithological reservoir,especially the special lithology reservoir and sandstone reservoir in mesozoic group in the outer space of development zone,there still exist some potential for petroleum prospecting.With mesozoic group of Zaoyuan Oilfield as the subject,this paper thoroughly analyzes its structural features of strata,reservoir features and main control factors of reservoir formation based on numerous data about earthquake,logging and assays.It analyzes conditions for known oil reservoir formation,summarizes enrichment laws for oil gas and mainly achieves following outcomes.The major faulted structure zones in the area develop on NE-SW and NW-SN,which divide the formation in Mesozoic reservoir into northern graben belt,central faulted-nose structure and southern horst belt.It has great significance for the formation of traps and distribution of oil gas.Research on reservoir characteristics of Mesozoic reservoir in Zaoyuan Oilfield,I find that two sets of andesite and sandstone reservoirs developed.By seismic facies,logging facies,reservoir prediction and other technologies,the eruptive pattern of andesite is identified to be central-erupting model-fissure type.There are mainly four facies belts.By analyzing known oil reservoir distribution laws,the single well of burst facies and surrounding effusive facies is found to have high yield,high cumulative yield and strong self-eruption abilities,so this area is favorable for prospecting.For sandstone of the mesozoic group,braided river is the major type of sedimentary facies and provenance comes from the northeast.The main area with overlaid multi-stage channels is the most favorable for reservoir development.With high thickness and good physical properties,reservoirs are facies belts helpful for hydrocarbon accumulation.By deeply exploring known reservoir forming conditions and summarizing oil and gas enrichment laws,it is inferred that the oil reservoir in the mesozoic group of the Zaoyuan Oilfield belongs to paleo-storage of the newborn,and structural reservoir of the major type of the mesozoic sandstone reservoir,including fault-block and fault-nose oil pools.The mesozoic andesite reservoir is structure-lithologic trap,where oil is mostly supplied by lateral docking of oil sources between reservoirs for direct vertical supply of oil gas" and"connecting faults with reservoirs for transverse transport of oil gas",so that a multiple oil and gas accumulation zone forms.In this survey,three target areas with great exploration potential are proposed,including the Fault Block Zao 1508 that has deployed 14 well locations with a maximum daily oil production of 120t in a single well in the early period and an increase in geological reserves by approximately 5,000,000t.Owing to their significant economic and social benefits,a virtuous cycle is formed for efficient development and further understanding of geology.Meanwhile,this survey may be used as references to certain extent for exploring the same types of oil reservoirs.