长庆气田马五_1储层裂缝类型及特征

FRACTURE TYPES AND CHARACTERISTICS OF THE Ma51 RESERVOIR IN CHANGQING GAS FIELD

长庆气田主力气层为马五１。通过观察大量岩心，从裂缝充填成分、碳氧同位素及其它地球化学特征着手，并结合地质、钻井、测试多种方法，对马五１储层裂缝类型、形成期次、成因类型划分以及裂缝形成的地质因素进行深入研究分析，总结出马五１储层裂缝类型及特征。马五１储层裂缝类型主要有四种，即垂直缝、斜交缝、水平缝及网状缝；马五１储层裂缝成因类型多，其中对储层渗流作用影响较大的主要有两大类，即构造缝和风化缝；据裂缝充填物碳氧同位素测定、包裹体光谱成分以及探针成分分析，马五１储层裂缝形成期主要有三期。第一期为加里东期，形成各类风化缝；第二期为燕山中期，是一次重要的构造破裂期，主要形成构造缝；第三期为燕山晚—喜山早期；风化缝的形成主要与风化岩溶作用形成地貌条件、岩层产状等因素有关；

The Ma51 reservoir is the main gas reservoir in Changqing gas field.In this paper,the fracture types,formation stage,genetic types division and geological factors forming fractures are thoroughly studied and analyzed,through observing a large number of the core,starting with the crack filler composition,carbonoxygen isotope and other geochemical characteristics and adopting geological,drilling and testing methods,and the fracture types and feature of Ma51 reservoir are summarized as follows:the main fracture types of Ma51 reservoir are four types:vertical,oblique,horizontal and braided.Although the genetic types of the fractures in Ma51 are many,the main types that have a great influence on the percolation flow of the reservoir are two types,i.e.structural fracture and weathered fracture.According to carbonoxygen isotope assay of the crack filler in the fractures and spectrum analysis and needle probe analysis of the inclusion enclave,the formation stages of Ma51 reservoir are mainly three,i.e.:(1)Caledonian stage,in which all kinds of weathered fractures have been formed;(2)midstage of Yanshan movement,which is an important structureruptured stage,mainly forming structural fractures;(3)late Yanshan stage to early Himalayan stage.The formation of the weathered fractures is mainly related to the geomorphologic condition due to Karstification and the occurrence of the rock statum,but the formation of structural fractures is related to the condition of palaeostress field and the mechanics property of rock itself.