辽河盆地东部凹陷新生代火山岩裂缝与油气

辽河盆地是中、新生代发育起来的裂谷盆地。东部凹陷是辽河盆地的一部分,频繁的火山活动是本区的重要特征之一。新生代时期,受燕山运动、喜山运动Ⅰ、Ⅱ、Ⅲ幕的强烈影响,本区喷发了多期强度不等的火山岩。本区火山岩油藏的裂缝类型主要有以下几种:原生裂缝和次生裂缝。原生裂缝是岩浆冷凝结晶过程中形成的裂缝;次生裂缝是火山岩及其原生裂缝系统受后期构造运动、溶蚀、风化等作用改造而形成的裂缝。火山岩的岩石类型、喷发形式和所处的构造位置是火山岩裂缝形成的内因,构造运动、溶蚀作用、风化作用是火山岩裂缝形成的主要外因。这种内因和外因的联合作用,形成本区的原生裂缝和次生裂缝叠加的复杂裂缝系统。其中,构造裂缝是本区最主要的次生裂缝,裂缝反映出的应力场与区域或局部的应力场一致。不同级别、不同期次的断层活动过程也是局部或区域裂缝的产生和叠加的过程。本区构造裂缝的产生与燕山运动、喜山运动Ⅰ、Ⅱ、Ⅲ幕的强烈影响密切相关。裂缝的发育是形成本火山岩油气藏的关键,本区有效的裂缝为构造裂缝和溶蚀裂缝,构造裂缝预测是钻前裂缝预测的有效手段,裂缝与孔隙的良好组合是本区火山岩油气藏发育的优势。

The Fracture and Oil/Gas of Cenozoic Volcanic Rock of the Eastern Sag of Liaohe Basin

Liaohe basin is a rift basin developed in the Mesozoic and Cenozoic. Eastern sag is a segment of Liaohe basin. There were different intensity of volcanic expulsion influenced by Yanshanian and the episodesⅠ?Ⅱ?Ⅲ of Himallayian movement. There were several major types of fractures of the volcanic rock reservoirs: primary fracture and secondary fracture. Primary fracture were formed during the lava crystal and the secondary fracture generated during the volcanic reconstruction by tectonic movement, and wind action, solution. The internal causes of the volcanic rock fracture formation were the rock type, the style of expulsion and the tectonic position; the external causes of the volcanic rock fracture were the tectonic movement, solution and wind action. The superposition of the fracture system in the area caused by the uniting of the internal causes and the external causes. Thereunto, tectonic fracture was the main secondary fracture, the reflection of the stress field accorded with regional or local stress field. The courses of different distinction, different period fault activity were the courses of generating and superposition of the regional or local fracture. The generating of tectonic fracture was tightly relative with Yanshanian and the episodesⅠ?Ⅱ?Ⅲ of Himallayian movement. The development of fracture was the key of the oil and gas pool formation in the area, the effective fractures were tectonic and solutional fractures, the tectonic fracture forecast is the effective means of the forecast fractures before drilling, and the fracture fitted well with pore was the advantage of the development of volcanic oil and gas pool.