【作者】 袁海锋；

【导师】 徐国盛；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2008， 博士

【副题名】以川东南丁山构造和川中安平店—高石梯构造为例

【摘要】 本论文为国家重点基础研究发展计划（973）课题《中国海相碳酸盐岩层系油气富集机理与分布预测》（课题编号:2005CB422100）06子课题—中国海相碳酸盐岩层系深层油气成藏机理（课题编号:2005CB422106）的部分研究成果。论文主要研究了川东南丁山构造及川中地区安平店-高石梯构造震旦系储层的成岩作用及其控制因素,刻画了孔隙演化过程。利用现今震旦系储层沥青生物标志物地球化学确定了震旦系储层沥青的主要源岩。利用磷灰石裂变径迹技术和Easy%Ro化学动力学模型模拟计算了震旦系—下古生界的地温场演变,利用包裹体分析及PVTX热动力学模拟技术恢复了包裹体被捕获时的古压力,指出在特定的温度和压力背景下,震旦系古气藏中的天然气主要为水溶气。根据震旦系-下古生界储层孔、洞、缝充填物的相对关系,结合流体包裹体特征及锶、碳、氧稳定同位素特征确定了流体充注序列及充注期次。重点研究了震旦系气藏的成藏机理,揭示了油气生成、运移、聚集、散失、储层孔隙演化、圈闭形成（改造）过程在时间上和空间上的动态匹配关系,建立了油气的多期成藏及其演化模式,系统的总结了四川盆地震旦系成藏机理和成藏特征,论文取得的主要成果如下。（1）震旦系储层的成岩作用主要为白云岩化、重结晶作用、硅化、膏化及溶蚀充填作用等,可以识别出34种成岩作用。白云岩化作用对灯影组储集物性影响有限,晚期硅化胶结作用对孔隙度影响较大。震旦纪末的桐湾运动使灯影组受岩溶改造强烈;构造岩溶与有机酸深埋岩溶可使储层的孔隙度增加,与之相伴生的重结晶作用可抵制成岩阶段的部分胶结作用所导致的孔隙减少,是震旦系储层孔隙保持的主要原因。由于震旦系储层埋藏历史长,众多的成岩作用改造致使其孔隙演化过程复杂,成岩作用与流体充注的相似性使不同构造带孔隙演化过程具有一定相似性。（2）震旦系主要发育有三期破裂作用:第一期为大、中低角度裂缝,形成于中—深埋藏环境;第二期形成于深埋藏过程,区域有机质成熟后—喜马拉雅期前;第三期为构造松弛形成的张裂缝,形成于干气阶段或更早的构造阶段。破裂作用在早期溶蚀孔洞基本被充填的情况上,可增加储层的“孔隙度”,并极大地改善储层的渗透性。（3）震旦系—下古生界储层沥青及源岩的生物标志物研究表明,川中地区安平店—高石梯构造带寒武系源岩的沉积环境为具有一定盐度的还原环境,生物主要来自于低等水生生物的菌藻类;奥陶系、寒武系及震旦系储层沥青的各种生标指纹均可以与寒武系泥岩对比,他们主要来自寒武系泥质烃源岩。合川12井二叠系储层沥青的源岩应可能主要为志留系泥岩,寒武系洗象池群储层沥青的源岩应主要为寒武系泥岩。川东南地区丁山构造震旦系储层沥青均来自寒武系泥岩。寒武系石冷水组岩屑中软沥青样品的源岩与寒武系泥岩不具明显的亲缘关系,可能主要来自上覆志留系龙马溪组烃源岩,因此,寒武系储层沥青表现出混源的特征。（4）对于过、高成熟阶段的沥青样品,甾烷异构化参数发生了“倒转”,已经失去了表征成熟度的意义。经研究发现,Ts/（Ts+Tm）或Ts/Tm生标参数能够区分不同成熟度及沉积环境所形成的沥青;该比值所反应的相对的成熟度的大小与Pr/nC₁₇-Ph/nC₁₈关系所反应的成熟度及所测定的沥青反射率基本一致,能够反应样品的相对成熟度的高低。（5）利用磷灰石裂变径迹技术和Easy%Ro化学动力学模型计算了川东南丁山1井和川中地区安平1井的古地温演变,震旦系和寒武系古地温梯度是变化的,大致都经历了降低—升高—降低的过程。恢复了川东南与川中地区地层埋藏史与烃源岩热演化史。经川东南丁山1井寒武系和川中安平1井震旦系储层中的流体包裹体激光拉曼分析表明,储层中的甲烷有一部分为溶解态甲烷,它们以水溶气的形式赋存于盐水流体中。利用包裹体的均一温度和模拟的包裹体压力,确定了水对甲烷的溶解能力。结合地层隆升—沉降史及地温场、古压力的变化,根据岩心孔洞缝中矿物的充填顺序,刻画了水溶气的形成及捕获过程。（6）根据储层孔、洞、缝中的矿物充填顺序及锶、碳、氧稳定同位素地球化学研究,川中地区和川东南地区震旦系—下古生界储层至少存在6期流体充注。从第一世代的矿物到第四世代的矿物,记录的是岩层被逐渐深埋的过程,第五世代矿物→第六世代矿物,则记录了隆升过程中溶解于水中的天然气发生气水分离→盐水流体与沥青分离沉淀的过程。这一系列的流体充注序列上代表了从深埋到隆升过程中,流体充注的全过程。（7）震旦系—下古生界围岩和孔、洞、缝充填物的锶、碳、氧稳定同位素地球化学揭示,所充注的盐水流体不是来自于围岩自身,均是外源的。震旦系储层中具有多期油气充注,上覆寒武系、奥陶系储层中可能只有一期石油充注。不同层位均有相同来源的油藏流体和盐水流体充注,暗示着断裂和裂缝可能是导致流体穿层运移的主要垂向输导体系。（8）川东南丁山构造震旦系天然气藏的演化主要经历了以下几个阶段:①志留纪末期古油藏的形成阶段;②加里东运动造成的地层抬升剥蚀期的古油藏破坏阶段;③早二叠纪—早中三叠纪寒武系源岩二次生烃油气再充注阶段;③中、晚三叠纪—中、晚侏罗纪,油裂解气及水溶气形成阶段;④晚白垩纪末,天然气脱溶,古气藏的破坏阶段。川中安平店—高石梯构造带震旦系油气成藏的演化与丁山构造震旦系相似,与丁山构造所不同的是晚白垩纪以来的地层隆升主要为天然气出水脱溶和古气藏的调整阶段,仅仅是天然气的散失、转移和再分配过程,致使安平店—高石梯构造带震旦系气藏形成现今的残留气藏。（9）四川盆地震旦系-下古生界天然气的成藏过程是一个古油藏→古气藏→现今（调整改造型）气藏的演化过程,其主要特征有:①源岩的早期生排烃,为古油藏形成和破坏阶段;②源岩的二次生烃,发生于二叠纪—三叠纪的有机质成熟生烃和排烃过程,油气早期多期成藏,表现为生排烃差异、多期油气运聚;③发生于中侏罗世及以前的原油热裂解产生天然气和沥青的过程,导致天然气中期成藏,表现为深埋高温、油气转化;④发生于喜马拉雅期构造圈闭的形成和隆升剥蚀过程,致使天然气晚期成藏,表现为隆升剥蚀、能量场调整、天然气出水脱溶、晚期破坏或重新分配成藏。更多还原

【Abstract】 The paper mainly discussed the diagenesis and its control factors of sinian reservoirs in DingShan structure and AnPingDian-GaoShiTi structure, southeast and middle of Sichuang basin, then drew its porosity evolution.Using the characteristics of biological maker in simian reservoirs bitumen, oil source could be identified. Based on apatite fission track analysis and Easy%Ro chemical kinetics model, geothermal system of Sinian—Lower Palaeozoic could be simulated.The palaeopressure could be recovered by the analysis of fluid inclusion and stimulation of PVTX thermodymamic when these inclusions were captured. So the natural gas in sinian reservoirs exist as Water-soluble gas due to the condition of the particular temperature and pressuer.In the sinian-lower palaeoozoic reservoir, Based on the relative order of fillers in hole,bore and fracture, combining with characteristic of fluid inclusion and isotope of Sr, C and O, the sequence and stage of charging of fluid could be determined. The paper pays attention to the mechanism of gas accumulation in sinian reservoirs, and reveal the dynamics relationships matched with each other in the time-space scales during the hydrocarbon generation, migration, accumulation,dissipating, reservoir evolution and trap formation, and then build the evolution and model of hydrocarbon generation, accumulation of muti-stage and sum up the mechanism and feature of hydrocarbon accumulation systematically in sinian of Sichuan Basin.（1）The diagenesises of Zinian reservoir mainly include dolomitizaton, recrystallization, silication, gypsification,denudation, packing action, and so on, which could be categoried into thirty-four diagenesis. Dolomitizaton impact on the reservoir quality of Denying Formation, but silication which happened at late period effected the reservoir quality more seriously. Porosity increased because of karstifacition resulted from tectonic movement and organic acid, while recrystallization could resist part of cementation which can lead to decrease of porosity in diagenesis stage.That was why pore space in Zinian reservoirs could be maintained. Sinian reservoirs underwent a long time burial and the multitudinous diagenesises which made the porosity evolution complicated. There were similarity between each other in different tectonic belts due to their similar diagensises and fluid charging. （2）There were there-stage cataclasises in Zinian:the first stage developed big,middle-low angle fracture in middle-deep burial; the second stage formed fracture in deep burial after organic matured but before Himalayan epoch;the third stage developed gash fracture from tectonically relaxation in the phase of dry gas or earlier. Cataclasises could increase porosity in the early time when emposieus were infilled and improved permeability of reservoir.（3） Research on reservoir bitumen and possible source rock of Zinian-lower palaeozoic,their biomarker indicated that, 1)in Anpingdian-Gaoshiti tectonic belt, source rock in Cambrian was in anoxic and deoxidated environment having some salinity when it was deposited, and living beings were such low aquatic life as homoneneae; All of the bitumen in Ordovician, Cambrian and Sinian could be compared with mudstone in Cambrian by fingerprint, as concluded that the bitumen came from mudstone in Cambrian.Reservoir bitumen in Permian in Well Hechuan12 probably came from Silurian mudstone, and that in Xixiangchi group of Cambrian come from mudstone in Cambrian. All of Zinian reservoir bitumen of Dingshan Structure in southeast Sichuan area came from mudstone in Cambrian.Bitumen in debris of Shenglengshui Formation of Cambrian have no affiliation with Cambrian mudstone, which likely came from Longmaxi Formation of overlying Silurian. So Cambrian reservoir bitumen show the feature of multiple source.（4）As for bitumen of post-high maturity, sterane isomerization parameter came about reversal, which cannot be identified the maturity. Research indicated such biomarkers parameter as Ts/（Ts+Tm） or Ts/Tm could distinguish that bitumen of different maturity and depositonal environment. These parameters accorded with variance of Pr/nC₁₇-Ph/nC₁₈ and bitumen reflectance which can also reflect the relative maturity.（5） Based on apatite fission track and Easy%Ro chemical kinetics model, palaeogeothermal could be calculated in well Dingsan 1 and Well Anping 1. The geothermal gradient of Cambrian and Sinian varied from decreasing to increasing, and to decreasing again. The burial history of strata and thermal evolutionhsitroy of source rokcs was reconstructed. Laser Raman spectroscopy analysis for fluid inclusion in reservoirs of Cambrian in Well Dingsan 1, and of Sinian in Well Anping 1 .These indicated that a part of methane in reservoir was soluble, they existed in the saline water in the form of soluble-water gas. Using fluid inclusion homogenization temperature and analog inclusion pressure, dissolving capacity of methane in water can be confirmed. Combined with burial history, evolution of temperature and pressure with filling sequence of mineral in core hole, bore and fissiure, the formation and capture of water-soluble gas can be displayed.（6）Based on filling sequence of mineral in core hole, bore and fissure, and the isotope of Sr,C,O, Sinian-Lower palaeozoic reservoirs underwent fluid charging at least six stages.From the first stage to the forth stage, mineral recorded the process of burial. From the fifth to the sixth stage, mineral recorded the paration processse of gas and water and the separation process of saline water and bitumen, bitumen depositing.The sequence of fluid charging represented the full sequence of fluid charging from deep burial to uplifting.（7）Isotope of Sr,C,0 of mineral in core hole,bore and fissiur revealed that the saline water wasn’t from adjacent rock but allogenetic. Reservoir in Sinian presented multi-phase chargings, while that in overlying Cambrian and Ordovician probably appeared to be only one stage of fluid charging. Hydrocarbon and saline water in different layers coming from the same source, suggested that fault and fractures play the part of the main conduction systems which fluid migrated vertically.（8）Sinian oil and gas reservoir evolved through such stages of DingShan structure,①Palaeo-oil pools formed in late Silurian.②Palaeo-oil pools were destroyed by the uplift and denudation in Caledonian event.③From early Permian to early-middle Triassic, source rock in Cambrian generated hydrocarbon secondly.④From middle-late Triassic to middle-late Jurassic, oil cracking to gas happened and water-soluble gas formated.⑤At the end of late Cretaceous, natural gas exsolution took place and palaeo-gas pools were destroyed. Zinian hydrocarbon accumulation in Anpindian-Gaositi tectonic belt was similar to that of Well Dingshan structure. But natural gas appeared to be lost, transferred and redistributed when its exsolution came about due to uplifting since late Cretaceous, which leaded to remnant gas pool in Anpindian-Gaositi tectonic belt.（9）Sinian-low Palaeozoic gas accumulating experienced from palaeo-oil pools to palaeo-gas pools, and adjustion and reformation, which were characterd as by①palaeo-oil pool developed and was destructed when hydrocarbon generated from source rock in the early stage;②the second hydrocarbon generation leaded to multi-stage hydrocarbon accumulation early when organic matter maturation, hydrocarbon generation and expelled during Permian and Triassic;③In the middle Jurassic or before, oil cracking to gas and bitumen formation due to deeply burial, result in high temperature of gas pool and oil transformation to gas.④In the Himalayan, strcture trap formation, and the uplifting and denudation lead to late accumulation of hydrocarbon, which features mainly are uplifting, denudation, energy field adjustion, gas exsolution from water, gas pools at later destruction and gas redistribution.更多还原