The Relationship Between The Abnormal Pressure And Accumulation In Yanchang Formation In Binchang Region, In South Of Ordos Basin

Existing exploration results show that the Triassic in the south of Ordos Basin has rich oil and gas resources. Previous studies were focused on the basic conditions of accumulation, on the lack of a systematic accumulation of knowledge rules. In order to further clarify the Triassic formation in the study area in southern Ordos basin oil and gas distribution and accumulation law, based on the summary analysis of the existing research achievement, the use of petroleum geology, accumulation dynamics, petroleum system. And the latest theory and analysis method, through mapping mudstone compaction curves, the rich county block mudstone compaction law. Using the method of equivalent depth, mudstone excess pressure, detailed carving excess pressure characteristics and influencing factors, combined with sand mudstone configuration relations, set up model for oil-gas migration and accumulation; According to the research of sedimentary, reservoir characteristics and overpressure, analysis the main controlling factors of hydrocarbon accumulation in the build numbering of hydrocarbon accumulation pattern. The main results are as follows:1. On the south of basin Ordos basin Bin chang area Chang 7 source rocks are identified, mainly for oil shale and black mudstone, shale electrical characteristic main performance is: natural gamma ray value is greater than 170 API, acoustic time more than 310 us/m, resistivity than 50 ?. M, density is less than 2.4 g/cm2. In the Bin chang area,hydrocarbon source rock thickness is in commonly 10 m, the thickness is larger in the study area in the northwest and northeast.2. In Ordos basin Bin chang area, the under-compaction do exist in the Mesozoic, the amplitude and the initial horizon of under-compaction development difference between different areas.(1) The under-compaction development decided by the sedimentary conditions, the coefficient with average of 3.04 x 10-4, reflecting the deposition rate, each layer of a relative development degree is decided by sand mudstone configuration.(2) Bin chang area under-compaction development two pressure cycle, most of the first cycle in straight group began to develop, the development at the bottom of the Chang 4 + 5, down slightly decreased; The second screw at the bottom of the rejection of most of the Wells in Chang 7 maximum, has the characteristics of amplitude down in turn reduce.3. The main factors influencing the under-compaction development have deposits, and hydrocarbon generation, faults and tectonic uplift. Fault on the disc under-voltage actual small release, but the impact on the under-compaction development range is limited; In the area with intense tectonic uplift, some under-compaction has been released in full; Increased as uplifting amplitude increase, denudation, under-compaction amplitude decreases, under-compaction development starting horizon also has a tendency to move down. By studying the Yi Shan slope and uplift of Wei Bei boundary surrounding Wells found that tectonic uplift pressure release, but Bin chang area still has pressure closed conditions. Factors influence the abnormal high pressure in Bin chang area as under-compaction and tectonic uplift.4. By studying the relationship between structure and hydrocarbon distribution of abnormal pressure is found that :(1) Power are mostly located in excess pressure in period of relatively low pressure section below, and the pressure transition section between two high voltage segment or normal pressure.(2) Excess pressure gradient change affect the production of oil and gas, gradient change big oil and gas well production.(3) By the Chang 7 oil source, requires fault communication down across the layer of oil and gas migration; d, Bin chang region development three types of the excess pressure structure, excess pressure structure control the oil and gas of the main hydrocarbon expulsion direction.The Bin chang area's pressure structure is divided into three categories:Tape?: excess pressure in high value at the bottom of the Chang 7 section, up to a Chang 6 period of slow decreases, and down to the Chang 8 period of drastically reduced, oil can be either upward migration can also be downward migration, due to large excess downward pressure gradient, the migration of oil to long period of easier.Tape?: excess pressure in high value at the bottom of the Chang 7 section, up to the Chang 6period of slow decreases, and down to the Chang 8 period of reduced sharply, to the bottom of the Chang 8 began to increase, compared to the first ? class difference in the Chang 8 accumulation effectTape?: Chang 7 paragraph does not appear in surplus pressure maximum, the excess pressure from Chang 6 to Chang 9 period of continuous increase, Chang 7 period of hydrocarbon generation of source rock oil is difficult to downwards Chang 8 period of migration, mainly from Chang 7 to Chang 6 paragraphs and above formation of migration.5. Through the study on the relationship between the abnormal pressure structure and configuration of sand shale, according to the principle of abnormal pressure compartment, established the spatial-temporal in the southern of Ordos basin Bin chang area's Mesozoic pressure compartment model for oil-gas migration and accumulation.6. The distribution of abnormal pressure characteristics show that mainly vertical migration of oil and gas, abnormal high pressure source reservoir residual differential pressure is a major power of spatial-temporal in the southern of Ordos basin Bin chang area's Mesozoic hydrocarbon accumulation.7. Based on the extension of the leader and the comprehensive research on the differences between the oil and gas enrichment, Chang 7 control factors of hydrocarbon accumulation: hydrocarbon source rocks features control the distribution of the reservoir. Large thickness and good source store contact relationship is the influencing factors of production. Reservoir property and sand body distribution control distribution of the reservoir horizon. Capping ability strong or weak control number of the oil and gas accumulation, and become the extension 7 section of the main controlling factors of hydrocarbon accumulation in the team leader8. In the southern of Ordos basin Bin chang area's The major factors to control oil and gas distribution in Bin chang area are as follows: the distribution of hydrocarbon source rock development control the reservoir. Abnormal high pressure and control the oil and gas migration conducting system; The structure of the pressure control of the oil and gas, the major direction of hydrocarbon expulsion resulted in different parts of the main reservoir. According to the main control factors predict the favorable area, and set up the oil and gas accumulation pressure compartment model.