【作者】 高阳；

【导师】 金强；

【作者基本信息】 中国石油大学 ， 地质资源与地质工程， 2011， 博士

【摘要】 散失控制了生物气分布和富集,但生物气成藏过程中散失作用是目前研究的空白。渤海湾盆地发现多种成因生物气,这些生物气的充注和散失过程复杂,明确不同成因类型生物气成藏过程中的散失方式,量化生物气散失行为是亟待解决的科学和实际问题。以天然气地质学和油气地球化学理论为指导,分析了生物气地球化学特征,并划分了生物气成因类型,并分析了不同成因类型生物气的成藏特征。研究认为,渤海湾盆地生物气主要有原生生物气、后生生物气和原油降解气。富有机质的未熟烃源岩是原生生物气成藏的物质基础,散失作用控制其富集程度。后生生物气形成的必要条件是烃源岩重新回到微生物作用带以及地表水侵入。沿断层下渗地表水与原油的相互作用控制了原油生物降解气生成,还认为断层活动与封闭性控制了后生生物气和原油降解气的散失。以成藏动力学和天然气运移理论为指导,分析了阳信沙一段原生生物气藏、单家寺新近系原油降解气藏和柳泉沙三段后生生物气藏的散失过程,建立了不同成因类型生物气的散失地质模型和相应的数学模型。研究发现,原生生物气主要散失方式包括沿盖层渗漏、沿输导层渗漏和垂向扩散,其中沿盖层渗漏对气藏破坏作用巨大,其散失速率可达10^-310^-1m³/s,能使一个工业规模气藏在短时间内渗漏殆尽。侧向渗漏是原生生物气成藏过程中最重要的散失方式,其散失速率约为10^-410^-3m3/s,控制了原生生物气藏的成藏效率。垂向扩散对生物气藏破坏作用较小,扩散速率仅10^-710^-6m³/s,仅能改变生物气在纵向分布。沿断层散失是原油降解气和后生生物气散失的主要方式,断层活动时生物气沿断层伴生裂隙以压管流方式高速散失。对单家寺原油降解气在断层活动时沿伴生裂隙的散失进行评价,其散失速率高达0.1¹.5m³/s,生物气不能成藏。断层停止活动后,生物气沿着断层破碎带的派生裂缝以达西流方式低速散失,较断层活动时大大降低,散失速率约10^-610^-5m³/Ma,且随埋深增加,派生裂缝在压实和胶结作用下逐渐愈合,散失速率也逐渐降低,这有利于原油降解气和后生生物气在晚期成藏。更多还原

【Abstract】 Biogas losses contol its distribution and accumulation, but biogas losses are less studied. There are many different genetic types of biogas in Bohaiwan Basin, and their charging and loss are complex. Analysis the loss ways of different genetic types of biogases and evaluate the loss behavior quantitatively help to understand the control factors of biogas accumulation.Take typical biogas reservoirs in Bohaiwan basin as examples, as guild of geochemical and natural gas geology, base on the geochemical characteristics of biogases, the genetic types of biogases in Bohaiwan Basin are divided, and the accumulation characteristics of biogas are studied. The genetic types of biogas in Bohaiwan Basins can be divided into primary-buired biogas, secondary buried biogas and oil-degradation biogas. Immature source rocks which riched in organic matters are material basis and loss control the accumulation of primary buried biogases. Source rocks back to microbial zone and surface water intrusion is the key facters for secondary buried biogas foramtion. Surface water intrusion and interaction with cruid oil control the formation of oil-degraded biogas. Fault controls the accumulation and hydrocarbon loss process of both secondary buried biogases and oil-degraded biogases.As the guide of kinetic theory of gas accumulation and hydrocarbon migration theory, take Yangxin Es1 primary biogas, Liuquan Es3 secondary biogas and Shanjiasi N oil-degraded biogas as examples, biogas loss processes are studied, and hydrocarbon losses geological models and mathematic models are established. Evaluation results show that: Leakage along the capcock or transport layer and diffusion are main loss ways of primary buried biogas. Leakage by caprock has a huge destructive effect on biogas reservoirs, and the loss rate can reached 10^-310^-1m³/s, it can make an industrial gas reservoir completely depleted in a short time. Leakage by transport layer control the biogas accumulation effectively, and loss rate of it is about 10^-410^-3m³/s. Diffusion play less important roles in biogas losses, but always impact vertical distribution of biogas. Biogas lost by fault associated crack with episodic pressure pipe flow during faulting period, and lost by derived fracture with Darcy leakage during fault resting stage, the loss rate of later is far below former. With the increase of depth, because of compaction and cementation, the porosity and permeability of derived fracture decrease, and the loss rate decreased. It indicates that the biogas reservoirs which controlled by fault are more likely to be accumulated in later stage.更多还原