Analysis On Main Controlling Factors Of Hydrocarbon Accumulation In Xujiahe 5^th Formation Of The Western Sichuan Depression

The west Sichuan Foreland basin is located in the west of Sichuan basin.From the tectonic background,the western Sichuan depression is located in the east of the nappe belt in the front of Longmen Mountain,and in the northwest margin of the Yangtze plate.From the north to the Micang Mountain,to the south,to the Emei-YWU fault block,to the west to the Longmen Mountain nappe tectonic belt,to the east to the middle of Sichuan uplift,to the north-east to the south-west direction of the long strip-shaped zone.The formation of the western Sichuan depression has experienced a complex evolutionary history and formed a rich natural gas resource.There are 23 wells developed and tested by Southwest Oil and Gas Company to the reservoir-forming system in the source of Xujiahe formation in western Sichuan area,and the production of test wells is relatively high,with 14 wells producing more than 10 000 square meters per day,of which well Xinchang 32 is 45,999 square meters per day.Well Xinchang 26is 33,999 square meters per day,indicating that there is a great potential natural gas exploration resource in the Xujiahe 5^th formation of the western Sichuan depression.In this paper,the research ideas of the Xujiahe 5^th formation in-source accumulation system are:using all drilling data,well logging data,analytical test data,etc.to carry out the analysis,?1?by analyzing the geochemical characteristics of the source rocks,In comparison of wells,find the intervals of high-quality source rocks,draw high-quality source rock thickness maps,analyze their distribution characteristics,and combine them with gas reservoirs to find their relationship with gas reservoirs.?2?Based on the analysis of the regional sedimentary environment,analyze the reservoir type of the Xujiahe 5^th formation reservoir,combine the physical property characteristics,the median particle size and the comparison of the wells,identify the high-quality reservoir segments,draw the corresponding sand body thickness map,and analyze the distribution characteristics.And its influence on gas reservoir.?3?Through the pressure prediction of a single well,understand the pressure system of the Xujiahe5^th formation,and analyze the impact of pressure on the gas reservoir.?4?Draw a model of the accumulation model and analyze the typical gas reservoir,and summarize the types of accumulation patterns and analysis of the main controlling factors of accumulation.Through the above steps,there are four main points in this paper:?1?Identify three sets of relatively good high-quality source rocks,namely the TX5-5,TX5-6 and TX5-7 sand layers,which will contain gas wells and gas producing wells and high quality.The water source rock thickness maps are superimposed and found that the gas wells are mainly concentrated in the vicinity of the high-quality source rocks,and the Xujiahe 5^th formation are mainly near-gas source.?2?The Xujiahe5^th formation reservoir type belongs to the low-porosity-extra-low permeability type,mainly the sand body of the delta front;three sets of relatively good quality reservoirs are identified,which are TX5-6,TX5-7 and TX5-8 sand respectively.The layer group;the location,physical properties and thickness of the reservoir all have an important impact on the accumulation and output of oil and gas.?3?Abnormal high pressure provides transport mobility,which is one of the main factors for efficient enrichment of Xujiahe 5^th formation of natural gas.?4?The main types of accumulation patterns are longitudinally stacked,and there are other types of patterns that have not been studied.The main controlling factors of hydrocarbon accumulation:gas source controls the scope and scale of gas reservoirs?mainly near gas source accumulation?;favorable phase belt determines the development of high-quality reservoirs;abnormal high pressure affects the efficient enrichment of natural gas.