【作者】 王冰洁；

【导师】 何生；

【作者基本信息】 中国地质大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 超压对油气成藏过程中的诸多方面如油气生成、运移和聚集具有重要的影响,超压分布特征及演化是含油气盆地中油气地质研究的重要方面,其研究也对钻井工程和油藏工程具有重要的意义。本文以东营凹陷沙三-四段烃源岩层系发育的大规模超压系统为研究对象,利用钻井、测井、地震以及测试分析等资料,在前人已有成果的基础上,深入研究了东营凹陷现今超压分布特征、成因和演化,并探讨了不同压力环境条件下油气驱动机制的差异性及其对油气运移和聚集的影响。通过对以上问题的研究,取得的成果认识如下：(1)东营凹陷为富烃超压凹陷,钻井揭示该凹陷大规模超压系统出现在沙三-四段烃源岩层系(沙四上亚段和沙三中-下亚段)。根据1485口探井的2400个钻杆测试(DST)数据,实测砂岩异常高压的埋深范围约在2200～4400m,剩余压力约为3.4～39.6MPa,压力系数在1.2～1.99；根据钻井和测井以及地震速度资料综合解释,超压带钻井泥浆密度明显增加,超压泥质岩层具有偏离正常趋势的异常高声波时差测井响应和异常低地震层速度响应特征,综合解释超压系统顶界面埋深在2200～2900m,对应地温在90～120℃,超压顶界面深度随着烃源岩层系顶界埋深的增加而增加。上述测井声波时差和地震层速度异常可以来预测东营凹陷大规模超压系统分布,根据单井超压计算结果和所建立的三维超压体模型,超压带整体分布特征和超压发育幅度与成熟烃源岩的累积厚度、埋深和热成熟生油作用具有明显的相关性,超压系统范围内烃源岩层系样品镜质体反射率(R0,%)分布在0.5～1.3%,成熟烃源岩累计厚度大,热演化程度处在大量生油阶段的区域控制了超压大规模发育的区带；断裂系统和输导性砂体对东营凹陷沙三～四段地层中发育的大规模超压系统的分布和结构变化具有重要影响。(2)油包裹体荧光颜色以黄白色(低中等成熟度)和蓝白色(高成熟度)为主,根据荧光光谱主峰波长特征可以将其划分为两种类型；发黄白色荧光和蓝白色荧光油包裹体的均一温度范围分别为70～100℃和100～130℃,与之对应的同期盐水包裹体的均一温度的范围为100～140℃和140～180℃。将共生的盐水包裹体平均温度在地层埋藏史和热史图中“投影”,由此得到东营凹陷沙四段和沙三段储层存在两个油气成藏期,第一期为东营组沉积期,时间大约为30-25Ma,第二期发生在明化镇组沉积期至今,时间大约为8～0Ma；不同荧光颜色的油包裹体可能为同一期油气充注造成,其差别主要是由油气来源不同导致成分不同所造成。从烃源岩成熟史和生排烃史特征来看,第二期油气充注期内,沙三下亚段和沙四上亚段干酪根转化率和生排烃量都大量增加,是最主要的成藏期。在每个成藏期内,利用流体包裹体古压力热动力学模拟的方法都检测到超压发育,根据试油结论,现今油层和油水同层发育超压,而水层和含油水层发育常压,判断其成因为砂岩储层的传递型超压。(3)对现今烃源岩压力场成因识别根据地层有效应力对欠压实和生油增压两种不同超压机制具有不同响应特征的原理,利用实测流体压力(DST)测试结果,结合声波和密度测井资料,对超压段所识别的不均衡压实作用和生油作用两种超压成因机制下的实测压力和有效应力随深度变化特征进行了分析,结果表明：①两种不同成因机制下的实测压力和有效应力特征具有明显的差异性,不均衡压实作用在压实过程中流体排出受阻,承担上覆部分岩层压力形成超压,表现为阻止地层有效应力增大,因此其实测超压增加段与静岩压力增加趋势大体一致,而有效应力随深度基本保持不变；生油作用在岩层正常压实固结之后形成超压,发育程度不受上覆岩层压力的影响,因此超压的增加在深度上与上覆岩层压力增加不具有一致性,且超压对有效应力的影响不同于不均衡压实作用；②这两种不同的超压成因使得有效应力的变化随着声波速度出现加载和卸载两种趋势线,可以用其来判断超压成因,利用实测资料计算的有效应力结果说明了东营凹陷超压成因机制包括欠压实作用和生油作用,但欠压实作用形成超压的范围和规模较小,平面上主要分布在利津洼陷北带和牛庄洼陷东部地区,埋深主要在2000-3200m的范围内,而生油作用对深部大规模超压和中等-强超压的形成至关重要,所以,现今超压系统主要是生油作用所致。(4)利用数值模拟的方法结合流体包裹体热动力学模拟结果说明,第一期超压的成因机制可能以欠压实作用为主。①生油增压的计算结果说明第一期超压发育期内由于生油增压一方面很难达到泥岩的破裂压力程度,另一方面其生成的超压幅度要小于流体包裹体热动力学模拟结果,所以,单纯以生油作用作为超压的成因很难对原油从烃源岩中的排出产生影响；②根据沉积速率计算结果,地层在沙三段沉积期经历了快速沉积过程,沉积速度可以达到800～1000m/Ma,为沙三下亚段和沙四上亚段大套泥岩发生欠压实作用形成异常高压提供了有利的条件；因此,欠压实开始形成的时期为沙三段地层沉积时期,早于第一期成藏期,埋深在1000～2000m的范围内。(5)烃源岩成熟史、生排烃史模拟和流体势计算结果表明：①主力烃源岩段沙三中、下亚段现今成熟度(R0%)区内主要分布在0.3～1.0%之间,沙四上亚段现今成熟度(R0%)区内主要分布在0.5～1.1%之间,洼陷内深凹区的成熟度高于洼陷边缘,现今仍处于大量生油阶段；②东营凹陷烃源岩层系的生、排烃过程可以分为三个阶段,至少存在两期原油的生成和排出,早期为30～25Ma,晚期为16～0Ma,其中以晚期为主,特别是距今5Ma(馆陶组沉积末期)以来,石油大量生成并排出；③流体势计算结果结果显示围绕各个深洼区的边缘和中央断裂带是有利的油气聚集区；其中,沙四上亚段在中央断裂带聚集的油气沿通源断裂和输导性砂体作垂向和横向上的运移；整体上,油气在三维空间中从高油势区向低油势区运移并聚集。(6)根据研究区2000余口探井的实测地压和油田水化学资料,结合储层超压演化,利用水化学场的成因特征,研究了超压系统演化过程对地层流体运聚产生的影响,即超压作用下流体运移特征。结果表明：①在垂向上,2200m之上常压系统(沙二段至馆陶组)地层水矿化度一般<100g/l,属于咸水范畴；2200m之下的超压系统(沙四和沙三段)部分地层水矿化度值>100g/l,最高达336g/l,属于盐水范畴；②在平面上,东营凹陷东部地层水矿化度值高于西部,北带高于南部,沙三段和沙二段高矿化度地层水在凹陷中心沿断裂带分布,沙四段地层水矿化度以东营北带洼陷区为中心呈环带状向外减小；③东营凹陷地层水离子间的关系和组合特征说明,在水化学场和超压系统耦合作用下,超压流体封存箱中的水-岩相互作用对凹陷中心氯化钙型高矿化度地层水的形成具有重要作用,高矿化度地层水形成可能某种程度上受到沙四段蒸发岩地层中盐类溶解作用的影响；④沙二、三段高矿化度地层水则主要是与沿断裂系统垂向运移的高矿化度沙四段地层水混合作用的结果。(7)东营组末期主要是来自沙四上亚段烃源岩的油气发生运移和成藏过程,最主要的油气充注成藏期是馆陶组末期5Ma以来的油气运移聚集。根据油气运移的能量条件(流体势模拟)和动力与阻力以及驱动机制分析,东营凹陷总体为与超压系统有关的油气驱动体系,但其中的超压系统、过渡压力系统和常压系统中的油气运聚特点存在明差异。超压环境下异常高压在相当大的程度上影响和控制着油气的运移指向、运移距离和富集程度；超压体边界、超压顶面附近、中等超压至弱超压或压力过渡带(压力系数<1.4)以及泄压区或与超压体有联系的常压系统中的储集层是有利的油气运移和富集的位置；强超压系统(压力系数>1.4)中的储层一般不利于油气充注和富集。更多还原

【Abstract】 Overpressure has an important impact to many aspects of the hydrocarbon accumulation process, such as hydrocarbon generation, migration and accumulation. Overpressure distribution characteristics and evolution is an important aspect of petroliferous basin geological research, the study also has a great significance for the drilling engineering and oilreservoir engineering. The source rocks of Es3and Es4in Dongying Depression, development of large-scale overpressured systems that as a research object, the use of drilling, well logging, seismic, and test analysis data, the basis of the results of our predecessors have been studied, Dongying Depression today overpressure distribution characteristics, origin and evolution, and discusses the differences of the different pressures environmental conditions, oil and gas drive mechanism and its oil and gas migration and accumulation. The results have obtained as follows:(1) Dongying Depression is a typical overpressured depression with abundant petroleum resources, a large-scale overpressured system occurs in the third and fourth members of the Shahejie Formation in the depression which evidenced by drill stem test (DST) data, and the source rocks are also existed within the overpressured system. Based on the2400DST data from1485wells, the burial depths of overpressured sandstone reservoirs range from2200to4400m with excess pressures of about3.4to39.6MPa and pressure coefficients of1.2to1.99. According to the integrated interpretation of drilling, well logging and seismic velocity data, the large-scale overpressured system is associated with significantly increase in drilling mud density, as well as abnormal high sonic transit times with deviation from the normal trend and low seismic interval velocity responding. By the integrated explanation, the burial depths of the top overpressured surface range from2200to2900m, corresponding formation temperatures ranging from90to120℃, the depths of top overpressure surface increase as the burial depths of source rocks deepen, the characteristics and magnitudes of overpressured system are coincident with the cumulative thickness and burial depth of mature source rocks, and thermal degradation oil-generation of source rocks. The increase of high sonic transit times and low seimic interval velocity responding can be used to predict the distribution of large-scale ovpressured system. This study indicates that the large-scale overpressured system is well developed where the cumulative thickness of mature source rocks is thick and source rocks remain in oil-generating stage of thermal evolution with vitrinite reflectance values of overpressured source rocks various from0.5to1.3%, and the fault system and sandstone transporting layers have an important influence on the distribution and construction change of the large-scale overpressured system in the third and fourth members of the Shahejie Formation of Dongying Depression.(2) The fluorescence color of oil inclusions are mainly yellow-white (medium maturity) and blue-white (high maturity), fluorescence spectrum peak wavelength characteristics can be divided into two types, yellow-white fluorescent and blue-white fluorescent oil inclusions homogenization temperatures range respectively from70℃to100℃and from100℃to130℃, and corresponding to the same period in aqueous inclusions of the homogenization temperature range from100℃to140℃and from140℃to180℃. The timing of oil charge by combining the homogenization temperatures of the aqueous fluid inclusions coeval with the oil inclusions with the inferred burial and geothermal histories of the host rocks, On the basis of the integration of the geohistory modeling results and the fluid inclusion homogenization temperature data, two episodes of oil charge are identified in the Es3and Es4reservoirs of the Dongying Depression at around the end of Ed depositional period (30～25Ma) and the Nm and Ng depositional period (8～0Ma), respectively. Different fluorescence colors of oil inclusions may be cause for the same period of the oil and gas injection, composition difference is mainly caused by the oil and gas from different sources. According to the source rock maturation history and hydrocarbon generation and expulsion history of the simulation results, in the second oil charge period, kerogen conversion rate and amount of hydrocarbon generation and expulsion is a substantial increase in the Es3x and Es4s formations, so it is the most significant oil charge period in Dongying Depression. In the first and second oil generation and charge period, the overpressure development was detected by thermodynamic modeling of fluid inclusions. In accordance with the conclusions of the test oil in the wells that reservoir and oil-water bed development overpressure, while the development of normal overpressure of the water layer, so the origin of overpressure in the sandstone is transfer of the overpressure from source rocks.(3) According to the different phenomenon of effective character which is controlled by origin overpressure mechanism of compaction disequilibrium and oil generation, the effective stress is calculated from the DST data and used to analyze the origin of overpressure. According to the results of the measured formation pressures from Drilling Stem Test (DST), sonic logging and density logging data, correlated the graphs of measured pressures and effective stress verses the depth, the origins of overpressures in the depression are both compaction disequilibrium and oil generation, this studies indicate that:①there are apparently separation differences of measured pressures and effective stress between undercompaction and oil generation. In the process of compaction disequilibrium, as a vertical sediment loading increases during burial, the pore fluid expulsion in shales is blocked and porosity reducing is not consistent with subsidence and rapid deposition, leading to the overpressures to occur due to the pore fluid undertaking a part of overburden stress. It seems that the effective stress increase is restricted, the overpressure trend is coincidence with the increase of overburden stress, and the values of effective stress verses the depth is about a constant in this condition. However, when the overpressures are formed due to oil generation within the normally compacted shales, the degree of overpressures is not influence by lithostatic pressure on the overlying, and the trend of excess pressure increase with depth is not consistent with the overburden stress increase, the effective stress relating to the overpressures with the regime of oil generation is different from the overpressures caused by compaction disequilibrium;②using the relationship of effective stress and sonic velocity, the loading curve and the unloading curve can be described to explain the regimes of the overpressures caused by undercompaction and oil generation. Based on the calculated effective stresses using the measured data, the origins of overpressures in Dongying Depression are considered to be compaction disequilibrium and oil generation, but the overpressures caused by undercompaction are small with the relative shallow depths, and mainly distributed in the Lijin sag North with Niuzhuang sag eastern region. Oil generation is the important regime for the formation of deep basin-scale overpressures.(4) The results of numerical simulation method combined thermodynamic modeling of fluid inclusions indicate that the origin of overpressure in the first phase is mainly compaction disequilibrium.①Quantitative estimation of overpessure cause by oil generation shows that the the overpressure value cause by oil generation is difficult to reach the rupture stress levels in the mudstone, and this value less than the thermal dynamics simulation of the fluid inclusions. Therefore, the pure oil-generating role as the overpressure causes is difficult impact on the discharge of crude oil from source rocks;②According to the deposition rate calculation, the Es3deposition period experienced rapid deposition process in the first phase of generating overpressure, the deposition rate can reach800-1000m/Ma, and the thick layers of mudstone occur compaction disequilibrium in Es3x and Es4s is provide favorable conditions for generating abnormal high pressure. Therore compaction disequilibrium began to form overpressure in a period of Es3formation during the deposition and earlier than the first phase of the Petroleum generation and charge, the depth range from1000m to2000m.(5) Source rock maturation history, and expulsion of the hydrocarbon generation history modeling and fluid potential calculation results show that:①The maturity (Ro%) values of main source rocks in Es3z and Es3x layers range from0.3%to1.0%, while those of Es4s layer range from0.5%to1.1%, and it is lower in the shallow edge area than in the deep depression, where the source rocks are supposed to generate mass oil at present;②The generation and expulsion processes can be divided into three stages, and there are at least two periods of oil generation and expulsion, the first one occurring from30Ma to25Ma, the second one occurring from16Ma to OMa, which is more important in the mean of oil generation and expulsion, particularly from5Ma to the present (the end of Guantao Formation in Neogene);③Simulation results show that around the edge of the sag areas and the central fault zone is favorable for hydrocarbon accumulation area, oil and gas gathering in the central fault zone in Es4s through the fracture and transporting sand for the vertical and lateral migration. On the whole, the oil from the high oil potential in the three-dimensional space to the low oil potential migration and aggregation.(6) According to the study area more than2,000wells in the measured pressure and the oil field water chemistry data, combined with the reservoir overpressure evolution, the use of the genesis of the water chemistry to study the impact of the overpressure system evolution process of formation fluid migration and accumulation, that is fluid migration features under the influence of the overpressure. The result are showed as follows:①In the normally pressure system (from Es2to Qp), which the depth above2200m, the total dissolved solid lower than100g/l, it belongs to the salt water areas; In the overpressure system (Es3and Es4), which the depth under2200m, the total dissolved solid higher than100g/l, up to336g/l, it belongs to saline areas;②In the east of the Dongying Depression, the total dissolved solid is higher than west, and higher in the north than south, in Es2and Es3, the distribution of high total dissolved formation water along the fault zone, and in Es4, the distribution of high total dissolved formation water as the center with north of Dongying Depression, was reduced to outside as zonal;③The relationship between plasma and assemblages shows:in the condition of the matched relationship between the formation water and overpressure system, the high total dissolved solid formation water maybe from the salts dissolved of evaporate formation in Es4, in the evolution process of the water chemical field, the CaCl2formation water have high total dissolved solid is formed by the water-rock interaction;④In Es2and Es3, high salinity formation water is mainly the result of mixing of high salinity Es4formation water vertical migration along fault systems.(7) The end of Ed deposition from Es4s source rocks of oil and gas migration and accumulation process. The most important oil and gas charge reservoir of hydrocarbon migration and accumulation since the late Guantao group (5Ma). Analysis of the energy conditions (fluid potential of hydrocarbon migration simulation), power and resistance as well as the drive mechanism, although Dongying Depression is the oil and gas-driven system with overpressure system, in the overpressure system, hydrocarbon migration and accumulation characteristics of the transition pressure and normal pressure systems existence of significant differences. Abnormal high pressure in the overpressure environment influence and control the direction of hydrocarbon migration, migration distance and the degree of hydrocarbon accumulation to a large extent. The reservoir in the boundary and top of overporessure, weak overpressure or pressure transition zone (pressure coefficient<1.4) and pressure relief area or the normal pressure system which have the realation with the overpressure body system is favorablethe location are hydrocarbon migration and accumulation, high overpressure system (reservoir pressure coefficient>1.4) are generally not conducive to oil and gas charge and enrichment.更多还原