火山岩圈闭识别描述方法及其应用

Method of identifying and characterizing of volcanic traps and its application

  • 摘要: 中国沉积盆地内火山岩分布广泛,松辽、准噶尔及四川等盆地不断取得重大突破与发现,火山岩已成为我国油气勘探的重要领域之一。松辽盆地长岭断陷发育火石岭组和营城组火山岩,是油气增储上产的重要领域,但其勘探成效直接取决于对火山岩圈闭的识别与刻画成果。与碎屑岩圈闭相比,火山岩圈闭成藏条件要求更为苛刻,储层条件、侧向及顶底板封堵条件是控制火山岩圈闭有效性关键要素。在解剖已发现火山岩油气藏基础上,通过攻关研究,提出了火山岩体刻画和火山岩储层的描述是火山岩圈闭识别的重点。以火山岩岩性圈闭为例形成了火山岩岩性圈闭识别描述“五步流程”,并实际应用于龙凤山鼻状构造带。钻后结果表明,火山岩岩性圈闭与钻前认识整体一致,圈闭落实可靠,验证了火山岩岩性圈闭识别描述技术方法的有效性,推进了长岭断陷火山岩的油气勘探,对国内其他盆地火山岩油气勘探具有一定的指导应用价值。

     

    Abstract: Volcanic rocks were widely developed in sedimentary basins in China. The Songliao, Junggar and Sichuan basins have got great research successes and exploration discoveries in igneous reservoirs, which have become one of the important fields for oil and gas exploration in China. In the Changling Fault Depression of Songliao Basin, volcanic rocks are widespread in the Huoshiling and Yingcheng formations, which have a good potential for reserve and production increase. However, the results of exploration were directly dependent on the technical level of identification and characterization of volcanic traps. The conditions of hydrocarbon accumulation in volcanic traps are more severe than those in clastic traps. The physical property of reservoir and sealing effectiveness of surrounding rocks are the key factors for the effectiveness of volcanic rock traps. Based on systematically analyzing the discovered volcanic reservoirs, it was pointed out that the characterization of volcanic rock mass and volcanic reservoir were the key points for the identification of volcanic traps. In this study, taking the volcanic lithologic trap as an example, a "five-step processing" for the identification and description of volcanic lithologic trap was proposed and applied to the Longfengshan nose structural belt in practice. The drilling results showed that the characteristics of volcanic traps were consistent with the research results before drilling, which confirmed the effectiveness and reliability of traps. It also verified that the identification and description methods of volcanic traps were effective for the Changling Fault Depression and had certain guiding application value in volcanic exploration in other basins of China.

     

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