The Sedimentary Characteristics And The Hydrocarbon Accumulation Law Of Jingbian Gas Field

Ordos Basin has a rich gas resource, however only few of it has been explored. The fifth member of Majiagou Formation in Ordovician is one of the favourable series of stratum, and Jingbian gas field is the major gas block. With the extension on the gas field development and production, it seems more urgent to keep the stable production and enlarge gas area and the reserves. Researching the distribution of oil and gas through applying new technology and method will be the fruitful measure to explore the eastern part of Jingbian Buried platform, so this paper is implemented.This paper is based on the fruits of the previous people. And it makes full use of the present materials that concerning to drilling, logging, gas testing and sample testing. Taking sedimentary theory as the academic guideline and applying geochemistry indexes correlation technology, this paper has defined the difference between high-evolution sea facies propelic-type gas and coal-formed gas firstly. Then it has confirmed the gas reservoir sedimentary environment and sedimentary model based on the sedimentary characteristics of lithology combination and the diagenesis. Thirdly, trough quantitative evaluation on residual karst strength, it has made sure the developing gas field zone. Fourthly, it has evaluated the seal ability of cap formation and reservoir features through analyzing the experiment and logging results. Last but not the least, through combining the methods of gas transportation, this paper has concluded the hydrocarbon accumulation law systematically and predicts the favourable exploration zone in the eastern part of Jingbian Buried platform.This paper not only defines the sedimentary environment in Jingbian gas field as tide-flat, but also makes sure that the source rock consists of carbonate in Ordovician mainly. It also finds epidiagenesis environment fresh-water diagenesis and shallow burial diagenesis can contribute to the accumulation and enlargement of stratum pores. At the same time, it finds that reservoir sedimentary diagenetic can control the storage and production of reservoir. Precarboniferous karst palaeogeomorphology in Jingbian gas field can control the development of the reservoir, and the type of gas reservoir is stratigraphic trap. Combining the source rocks, cap formation, reservoir, trap and analysis preservation condition, this paper concludes the Hydrocarbon Accumulation Law and gas accumulation condition in Jingbian gas field, proposes that Shan227 area, the eastern of Shan 106 area and the other three areas are the best zone to explore in the eastern part of Jingbian Buried platform.