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- Title
延川南气田近薄层煤层气开发实践及其示范意义.
- Authors
杨 松; 刘 晓; 申 建; 陈贞龙; 崔 彬; 张国林; 张文洪
- Abstract
Since the Yanchuannan gas field at the eastern margin of the Ordos Basin started to produce in 2013, No. 2 coal seam of the Lower Permian Shanxi Formation has produced 23.3×108 m³ natural gas cumulatively. After the implementation of development measures such as refracturing and nitrogen foam flushing, the gas field can only keep stable natural gas production. In order to ensure the efficient development of the Yanchuannan gas field, this paper focuses on the "near-thin" No. 10 coal seam (thickness <2 m) of Upper Carboniferous Taiyuan Formation underlying No. 2 coal seam, and figures out the geological-engineering conditions of No. 10 coalbed methane (CBM) by comparing No. 10 and No. 2 coal seams in terms of gas content, permeability and fracturability. In addition, the fracture morphology and gas production effect after enhanced fracturing are analyzed, and the exploration theory and development technology of near-thin bed CBM are developed. The following research results are obtained. First, No. 10 coal seam is deep and highly metamorphic, with high vitrinite content, low ash content and great gas generation potential. Second, No. 10 coal seam has strong adsorption capacity, and its roof and floor have a good sealing property and weak water content. Water retention environment is conducive to CBM preservation, with gas content up to 44 m³ /t, providing a good resource basis. Third, the cleat in the core of No. 10 coal seam is more developed, and the horizontal stress difference coefficient is large. Therefore, fracturing can hardly break through the roof and floor while easily inducing main fractures, so as to achieve higher fracturing formation efficiency and better fracturability. Fourth, the formation of enhanced fracturing can extend the reservoir fracture length "laterally" to make up for the insufficient "vertical" thickness and improve the recovery efficiency. After the application of this understanding, natural gas production is improved remarkably. In conclusion, in the development practice of near-thin bed CBM in the Yanchuannan gas field, the key technologies for the development of near-thin coal seam are developed in two aspects of geological condition and development technology. The development practice points out the direction of long-term stable gas production in the Yanchuannan gas field, and provides a new inspiration for the development of near-thin bed CBM in China's Qinshui Basin, Chuxiong Basin and other overlapped CBM reservoirs.
- Subjects
CHINA; COALBED methane; NATURAL gas production; GAS fields; ADSORPTION capacity; NATURAL gas; VITRINITE; COAL; GAS condensate reservoirs
- Publication
Natural Gas Industry, 2023, Vol 43, Issue 8, p90
- ISSN
1000-0976
- Publication type
Article
- DOI
10.3787/j.issn.1000-0976.2023.08.008