火山岩体追踪识别及其在气藏有效开发中的应用

陈欢庆 胡永乐 冉启全 闫林



摘 要:针对火山岩储层非均质性强烈、横向变化大、有效预测和开发难度大等问题,以松辽盆地徐东地区营城组一段火山岩储层为例,综合岩芯、测井、地震和分析测试等多种资料,在火山岩体发育基本特征表征基础上,从储层精细划分、岩相分类与储层物性分析、有利开发区带预测等方面,阐述了火山岩体追踪识别在气藏有效开发中的应用情况。结果表明:松辽盆地徐东地区单个火山岩体平面上面积多在20 km2,平均厚度多在300 m;在火山岩储层精细对比中,加入火山岩体的追踪识别可以解决精细分层界限穿越火山岩体的“穿时”矛盾;火山岩体与火山岩相关系密切;靠近火山口的构造高部位多为好储层发育和有利的开发区域。
关键词:火山岩;有利开发区带;地层对比;储层;岩相;营城组;徐东地区;松辽盆地
中图分类号:P618.130.2;TE122 文献标志码:A
Abstract: Volcanic reservoirs have the characteristics of strong anisotropism, large lateral variation, difficult effective prediction and exploitation. Taking the member 1 of Yingcheng Formation in Xudong area of Songliao Basin as an example, combined with the core, logging, seismic data and analytical test, the basic characteristics of volcanic bodies were described, and the application of tracing and identifying of volcanic bodies on the effective exploitation of gas reservoir was explained according to the detailed reservoir division, lithofacies classification and analysis of reservoir physical property, and prediction of favorable development area. The results show that the single volcanic body mainly extends to about 20 km2, and the average thickness is mostly about 300 m; tracing and identifying of volcanic bodies, which are added into detailed correlation of volcanic reservoir, can solve the contradiction that the time radiuses of volcanic edifices are longer than those of volcanic bodies, and the stratum boundary passes through the former but not the latter; the relationship between volcanic bodies and lithofacies can forecast the development rules of different kinds of volcanic lithofacies or sub-lithofacies and favorable development areas; the high position near volcanic vent mainly develops favorable reservoir, and is the favorable development area
Key words: volcanic rock; favorable development area; stratigraphic correlation; reservoir; lithofacies; Yingcheng Formation; Xudong area; Songliao Basin
0 引 言
随着世界范围内碎屑岩、碳酸盐岩油气勘探开发形势日益严峻,伴随着社会经济高速发展带来的油气消费量急剧增加,火山岩油气藏勘探开发逐渐引起研究者的兴趣,目前火山岩油气藏在世界范围内已成为油气勘探开发研究的热点和难点[1-11]。Kawamoto等在利用岩石学方法建立非均质性火山岩储层模型的过程中,通过火山岩体追踪识别,有效解决了利用井对比难以在一定范围内持续对比火山岩储层结构的难题[11]。火山岩储层由于受火山喷发作用控制,具有分布面积相对较小、横向变化大等特点,有效预测和开发难度很大。火山岩体与火山岩储层发育特征之间关系密切,受火山口分布位置和火山喷发旋回的共同控制,在同一火山喷发时期形成众多形态各异、规模不同的火山岩体。这些火山岩体相互叠置、彼此交错,在不同部位发育不同火山岩相,进而构成了储集性能各异的储层。本文通过追踪识别不同火山机构和火山岩体,明确火山岩相和储层空间发育规律;同时,通过分析火山岩有效储层与火山岩体的关系,实现火山岩储层有利开发区带的预测。
1 区域地质概况
松辽盆地火山岩油气资源丰富,盆地内分布着徐深气田、长岭气田等众多火山岩气田,本次研究区就位于徐深气田[12-16]。徐东地区位于徐家围子断陷中部,目前已成为徐深气田最重要的天然气目标区之一,研究的目的层位为下白垩统营城组一段(图1)[17]。本次研究将目的层自上而下划分为YC1Ⅰ1、YC1Ⅰ2、YC1Ⅱ1、YC1Ⅱ2和YC1Ⅲ等5个小层。火山岩气藏储层地质条件复杂,具有非均质性强烈、横向变化大、有效预测难等问题,因此,一直是制约气田有效开发的瓶颈问题。本次研究在火山岩体追踪识别和发育特征表征的基础上,探讨火山岩体追踪识别在火山岩储层精细划分对比、火山岩相研究和储层物性分析、火山岩有利开发区带评价等方面的应用,为火山岩气藏有效开发提供地质依据。