Factors controlling the formation and evolution of source rocks in the Shahezi Formation,Xujiaweizi fault depression,Songliao Basin

The types and quality of source rocks in the Shahezi Formation are the key factors affecting the distributions of various deep gas reservoirs in the Xujiaweizi fault depression in Songliao Basin.To clarify the quality differences and origins of different types of source rocks in the Shahezi Formation,this study reconstructed the sedimentary and water environment,determined the controlling effects of fault activity,sedimentary facies,and paleo-sedimentary environment on the quality of various source rocks,by making full use of seismic,logging,core,organic geochemical and element geochemical analysis.The results show that two types of source rocks developed in the Shahezi Formation,namely,mudstones and coals.The mudstones have a relatively high abundance of organic matter,which consists of type-Ⅱ kerogen and partial type-Ⅲ kerogen,and are concentrated in Sha-I Member.The coals have a high abundance of organic matter,which consist of type-Ⅲ kerogen,and are mainly distributed in Sha-Ⅱ Member.During the deposition of Sha-I Member,intense fault activity formed arrow,deep-water lacustrine basins with high salinity and strong reducibility on the downthrow sides of faults.During the deposition of Sha-II Member,fault activity progressively weakened,and the areas of lacustrine basins enlarged to their maximum values and became wide,shallow-water basins with low salinity and low reducibility.The development of source rocks was controlled by fault activity,sedimentary facies,and paleo-sedimentary environment.Fault activity formed accommodation space on the downthrown sides of faults for mudstone accumulation,thus determining mudstone thickness.The sedimentary environment controlled the organic matter input and determined the distribution of mudstones and coals.The paleo-sedimentary environment,which consisted of paleo-salinity,as well as paleo-water depth and redox conditions,affected the accumulation and preservation of organic matter and is the main controlling factor for the quality difference of various source rocks in the Shahezi Formation.

徐家围子断陷沙河子组主干断裂形成演化与地层剥蚀特征

主干断裂的活动控制着徐家围子断陷沙河子组的建造与改造。为了明确断裂活动,运用位移距离曲线方法系统分析了徐家围子断陷主干断裂的生长活动特征,通过不整合面下的同向轴特征分析了徐家围子断陷沙河子组沉积末期的剥蚀改造作用。结果表明:徐家围子断陷主干断裂分段特征明显,徐西断裂与宋西断裂在火石岭组沉积时期分别是数条分段的小断裂,在沙河子组沉积时期连通为整条断裂并持续控陷活动;徐中断裂在沙河子组沉积时期弱伸展弱控陷,在沙河子组沉积末期作为薄弱带发生压扭反转;徐东断裂带中的徐东正断层在沙河子组沉积时期弱控陷,徐东逆断层在营城组一段沉积末期的反转作用下形成;沙河子组沉积末期的反转作用对沙河子组厚度与构造格局产生明显改变,沿徐西断裂与宋西断裂存在较强的剥蚀,徐西断裂北端升平凸起尤为强烈,徐中断裂压扭反转产生一定的走滑分量并遭受剥蚀,徐东逆断层在营城组一段沉积末期的反转中形成,对沙河子组厚度无明显改变,但对徐东构造带构造格局产生明显影响。研究成果可为徐家围子断陷古构造恢复与进一步勘探提供理论参考。

致密砂砾岩成储界限及分级评价标准——以松辽盆地徐家围子断陷白垩系沙河子组为例

徐家围子断陷下白垩统沙河子组砂砾岩储层是松辽盆地深部重要的致密气藏储层,其孔渗关系复杂,给成储界限的厘定和储层分级评价带来挑战。针对沙河子组砂砾岩储层,采用水膜厚度法、充注动力法、试气产能法和力学平衡法厘定了理论下限、成藏下限、有效渗流下限和成储上限,根据不同成岩作用主控因素下的孔渗关系确定成储界限物性值。在此基础上,结合储层微观孔隙结构差异划分储层类型,建立致密储层分级评价标准,并利用测井资料将分级评价标准进行应用,为研究区致密气甜点区优选提供依据。将沙河子组砂砾岩分为常规储层、Ⅰ—Ⅳ级致密砂砾岩储层和非储层,成储界限与分级评价结果具有很好的匹配关系。其中,常规储层孔隙度大于9%,渗透率大于0.05×10^(-3)μm^(2);Ⅰ级致密储层孔隙度为8%~9%,渗透率为(0.01~0.05)×10^(-3)μm^(2);Ⅱ级致密储层孔隙度为5%~8%,渗透率为(0.001~0.01)×10^(-3)μm^(2);Ⅲ级致密储层孔隙度为3.5%~5%,渗透率为(0.2~1)×10^(-6)μm^(2);Ⅳ级致密储层孔隙度为2%~3.5%,渗透率为(0.05~0.2)×10^(-6)μm^(2);非储层的孔隙度小于2%,渗透率小于0.05×10^(-6)μm^(2)。致密砂砾岩气产量受控于致密储层类型;Ⅰ级、Ⅱ级致密储层是致密气高产的有利层段;徐家围子断陷北部安达—宋站地区有利储层厚度较大,为致密气勘探开发甜点区。

The Identification and Modeling of the Volcanic Weathering Crust in the Yingcheng Formation of the Xujiaweizi Fault Depression, Songliao Basin

Through the analysis of core descriptions, well-logs, seismic data, geochemical data and structural settings of the volcanic rock of the Yingcheng Formation in the Xujiaweizi fault depression, Songliao Basin, and the geological section of the Yingcheng Formation in the southeast uplift area, this work determined the existence of volcanic weathering crust exists in the study area. The identification marks on the volcanic weathering crust can be recognized on the scale of core, logging, seismic, geochemistry, etc. In the study area, the structure of this crust is divided into clay layer, leached zone, fracture zone and host rocks, which are 5-118 m thick （averaging 27.5 m）. The lithology of the weathering crust includes basalt, andesite, rhyolite and volcanic breccia, and the lithofacies are igneous effusive and extrusive facies. The volcanic weathering crusts are clustered together in the Dashen zone and the middle of the Xuzhong zone, whereas in the Shengshen zone and other parts of the Xuzhong zone, they have a relatively scattered distribution. It is a major volcanic reservoir bed, which covers an area of 2104.16 km2. According to the geotectonic setting of the Songliao Basin, the formation process of the weathering crust is complete. Combining the macroscopic and microscopic features of the weathering crust of the Yingcheng Formation in Xujiaweizi with the logging and three-dimensional seismic sections, we established a developmental model of the paleo uplift and a developmental model of the slope belt that coexists with the sag on the Xujiaweizi volcanic weathering crust. In addition, the relationship between the volcanic weathering crust and the formation and distribution of the oil/gas reservoir is discussed.

Development features of volcanic rocks of the Yingcheng Formation and their relationship with fault structure in the Xujiaweizi Fault Depression,Songliao Basin,China

The Xujiaweizi Fault Depression is located in the northern Songliao Basin,Northeast China.The exploration results show that the most favorable natural gas reservoirs are in the volcanic rocks of the Yingcheng Formation（K 1 yc）.Based on seismic interpretation,drill cores and the results of previous research,we analyzed the distribution of faults and the thickness of volcanic rocks in different periods of K 1 yc,and studied the relationship of volcanic activities and main faults.Volcanic rocks were formed in the Yingcheng period when the magma erupted along pre-existing fault zones.The volcanic activities strongly eroded the faults during the eruption process,which resulted in the structural traces in the seismic section being diffuse and unclear.The tectonic activities weakened in the study area in the depression stage.The analysis of seismic interpretation,thin section microscopy and drill cores revealed that a large number of fractures generated in the volcanic rocks were affected by later continued weak tectonic activities,which greatly improved the physical properties of volcanic reservoirs,and made the volcanic rocks of K 1 yc be favorable natural gas reservoirs.The above conclusions provide the basis to better understand the relationship of the volcanic rock distribution and faults,the mechanism of volcanic eruption and the formation of natural gas reservoirs in volcanic rocks.

A Study of the Migration and Accumulation Efficiency and the Genesis of Hydrocarbon Natural Gas in the Xujiaweizi Fault Depression

In order to investigate the migration and accumulation efficiency of hydrocarbon natural gas in the Xujiaweizi fault depression, and to provide new evidence for the classification of its genesis, a source rock pyrolysis experiment in a closed system was designed and carried out. Based on this, kinetic models for describing gas generation from organic matter and carbon isotope fractionation during this process were established, calibrated and then extrapolated to geologic conditions by combining the thermal history data of the Xushen-1 Well. The results indicate that the coal measures in the Xujiaweizi fault depression are typical ＂high-efficiency gas sources＂, the natural gas generated from them has a high migration and accumulation efficiency, and consequently a large-scale natural gas accumulation occurred in the area. The highly/over matured coal measures in the Xujiaweizi fault depression generate coaliferous gas with a high δ^13C1 value （〉 -20‰） at the late stage, making the carbon isotope composition of organic alkane gases abnormally heavy. In addition, the mixing and dissipation through the caprock of natural gas can result in the negative carbon isotope sequence （δ^13C1 〉δ^13C2 〉δ^13C3 〉δ^13C4） of organic alkane gases, and the dissipation can also lead to the abnormally heavy carbon isotope composition of organic alkane gases. As for the discovery of inorganic nonhydrocarbon gas reservoirs, it can only serve as an accessorial evidence rather than a direct evidence that the hydrocarbon gas is inorganic. As a result, it needs stronger evidence to classify the hydrocarbon natural gas in the Xujiaweizi fault depression as inorganic gas.

Fault Systems and their Control of Deep Gas Accumulations in Xujiaweizi Area

A study of faults and their control of deep gas accumulations has been made on the basis of dividing fault systems in the Xujiaweizi area. The study indicates two sets of fault systems are developed vertically in the Xujiaweizi area, including a lower fault system and an upper fault system. Formed in the period of the Huoshiling Formation to Yingcheng Formation, the lower fault system consists of five fault systems including Xuxi strike-slip extensional fault system, NE-trending extensional fault system, near-EW-trending regulating fault system, Xuzhong strike-slip fault system and Xudong strike-slip fault system. Formed in the period of Qingshankou Formation to Yaojia Formation, the upper fault system was affected mainly by the boundary conditions of the lower fault system, and thus plenty of muiti-directionally distributed dense fault zones were formed in the T2 reflection horizon. The Xuxi fault controlled the formation and distribution of Shahezi coal-measure source rocks, and Xuzhong and Xndong faults controlled the formation and distribution of volcanic reservoirs of Y1 Member and Y3 Member, respectively. In the forming period of the upper fault system, the Xuzhong fault was of successive strong activities and directly connected gas source rock reservoirs and volcanic reservoirs, so it is a strongly-charged direct gas source fault. The volcanic reservoir development zones of good physical properties that may be found near the Xuzhong fault are the favorable target zones for the next exploration of deep gas accumulations in Xujiaweizi area.

松辽盆地徐家围子断陷营城组火山地层期次划分及分布规律

基于大量钻井岩心、薄片、测井、同位素年龄和三维地震等资料,以营二段含煤火山碎屑沉积夹层为标准层,通过测井曲线识别火山地层界面,结合ECS测井中获取的Gd、Ti元素识别该火山地层界面的类型,建立松辽盆地北部徐家围子断陷营城组“三段六期次”火山地层序列。在此基础上,总结火山喷发期次界面特征,探讨营城组火山岩分布与深大断裂的关系。结果表明:营一段3个期次自下而上岩性分别为“中基性熔岩/砂砾岩→酸性(碎屑)熔岩/火山碎屑岩→酸性熔岩/火山碎屑岩”;营三段3个期次自下而上岩性分别为“酸性熔岩→中基性熔岩→酸性酸性(碎屑)熔岩/火山碎屑岩偶夹中基性熔岩”;期次间界面主要是风化壳、岩性界面和再搬运堆积物夹层;期次内地层界面通常是同岩性的小型风化壳,风化蚀变带和火山碎屑夹层;徐东地区T_(4-1)和T_(4)界面之间发育两套产状明显不同的火山岩是营一段不同期次火山喷发产物;营一段主要分布在徐东、徐西和升平-宋站地区,安达地区不发育;从早期到晚期火山喷发中心从南向北迁移,依次受徐中断裂→徐中断裂和徐东断裂南部→徐东断裂南部控制;营三段主要分布在安达、升平-宋站和徐西地区,徐东地区不发育;营三段火山岩在断陷北部从早期到晚期依次受徐西断裂→徐西断裂和徐东断裂→徐西断裂和徐东断裂控制;断陷南部火山岩主要受徐中断裂和徐西断裂共同控制。

徐家围子断陷兴城-丰乐地区营一段火山机构识别与刻画

兴城-丰乐地区营城组一段(K 1yc 1)火山岩作为有利的天然气储层,近年来关于岩性-岩相方面的研究较深入,但关于火山机构方面的研究与认识程度较低。综合应用岩心描述、薄片鉴定、测井识别以及地震相预测等技术方法,从岩性-岩相的识别与分析出发,对研究区营一段火山机构开展了系统与深入的研究。结果表明:①营一段火山岩储层主要发育火山熔岩与火山碎屑岩两大类,岩性复杂多样,以酸性流纹岩与凝灰岩为主;②火山岩岩相类型主要包括爆发相、溢流相、侵出相、火山通道相和火山沉积相5类大相及其相应的16类亚相,并以爆发相和溢流相为优势岩相;③营一段火山活动时期,工区内共发育8个规模较大的火山机构,可划分为火山碎屑岩型、熔岩型和复合型三大类;④火山机构的形成与演化明显受到宋西断裂的影响与控制,总体呈现北西-南东向的空间展布规律。本次研究所取得的认识,能够为研究区营一段火山岩天然气藏指明有利的勘探方向与目标。

致密气充注聚集机理及数理模型

致密气的气-水分布和产出非均质性虽已从实验和地质观察角度总结了相应认识规律,但一直缺少定量的数理模型揭示其聚集机理。从驱替-核磁物理模拟、考虑物质平衡和力学平衡的数值模拟以及实际地质观察3方面论证致密气充注聚集机理,结果显示致密气充注聚集时会在源-储界面附近优先形成含气饱和度稳定带,气源不足时,从源-储界面起,依次形成含气饱和度降低带和未充注带。源岩条件越好,排气量越多、超压越大,致密储集层含气饱和度稳定带和降低带越厚,整体含气饱和度越高;源岩条件有限时,致密储集层条件越好,孔渗越高、孔喉越大,含气饱和度稳定带和降低带厚度越薄,但含气饱和度高。致密气“甜点”有利层段发育在靠近源岩的优质储集层中,对应含气饱和度稳定带。基于数理模型的数值模拟结果很好地吻合了驱替-核磁物理模拟结果,并合理解释了松辽盆地徐家围子断陷深层和鄂尔多斯盆地临兴—皇甫致密气区的气-水分布和产出规律。

基于构造应变分析的裂缝预测方法及其应用

地层应变是构造裂缝产生的直接因素,根据构造应变大小可以预测构造裂缝发育的位置和强度,对研究区的主要裂缝发育区进行划分。文章以松辽盆地徐家围子断陷徐中地区营城组四段(简称营四段)为研究对象,在建立研究区精细的三维构造模型基础上,利用“构造恢复”方法实现研究区古构造恢复,通过开展有限应变值计算来预测构造裂缝的平面分布。研究表明:研究区营四段主要包括3个造缝期,即营城组末期、泉头组—青山口组时期、嫩江组时期,其中,营城组末期与泉头组—青山口组时期的构造变形较为强烈,是裂缝的主要形成时期。根据应变大小与试气产量的关系,将研究区划分为3类裂缝发育区,Ⅰ类裂缝发育区已钻井验证,表明利用构造应变对裂缝的预测结果可靠,Ⅱ类裂缝发育区可作为深层天然气的下一步挖潜的重要方向,Ⅲ类裂缝发育区产能较低,裂缝对储层的改造作用有限。

基于自然伽马测井的徐家围子断陷沉积层生热率研究

以徐家围子断陷为研究对象,研究生热率特点及其对地温场的影响。利用18口重点钻井内3062个自然伽马值,依据自然伽马与生热率(GR-A)之间的关系,计算其生热率的数值,建立岩性-生热率的对比图,估算研究区放射性物质生热对大地热流的贡献以及对深部地层的增温效应。结果显示,徐家围子的平均生热率为(1.229±0.394)μW/m^(3),岩性是生热率的主要影响因素,流纹岩的生热率最高,平均值为2.30μW/m^(3),凝灰岩、安山岩、火山角砾岩的生热率平均值也较高,分别为2.19μW/m^(3)、1.75μW/m^(3)、1.69μW/m^(3),而砾岩的生热率最低,为1.00μW/m^(3),砂岩的生热率平均值为1.07μW/m^(3),泥岩的生热率平均值为1.72μW/m^(3),煤的生热率平均值为1.32μW/m^(3)。根据地层生热率,估算徐家围子沉积层生热贡献的热流为4.92 mW/m^(2),约占地表总热流70.5 mW/m^(2)的7%,沉积层生热对地温梯度的贡献约为2.8℃/km,放射性生热对属于“热盆”的松辽盆地的地温场具有不容忽视的影响。

Tight gas charging and accumulation mechanisms and mathematical model

The gas-water distribution and production heterogeneity of tight gas reservoirs have been summarized from experimental and geological observations, but the charging and accumulation mechanisms have not been examined quantitatively by mathematical model. The tight gas charging and accumulation mechanisms were revealed from a combination of physical simulation of nuclear magnetic resonance coupling displacement, numerical simulation considering material and mechanical equilibria, as well as actual geological observation. The results show that gas migrates into tight rocks to preferentially form a gas saturation stabilization zone near the source-reservoir interface. When the gas source is insufficient, gas saturation reduction zone and uncharged zone are formed in sequence from the source-reservoir interface. The better the source rock conditions with more gas expulsion volume and higher overpressure, the thicker the gas saturation stabilization and reduction zones, and the higher the overall gas saturation. When the source rock conditions are limited, the better the tight reservoir conditions with higher porosity and permeability as well as larger pore throat, the thinner the gas saturation stabilization and reduction zones, but the gas saturation is high. The sweet spot of tight gas is developed in the high-quality reservoir near the source rock, which often corresponds to the gas saturation stabilization zone. The numerical simulation results by mathematical model agree well with the physical simulation results by nuclear magnetic resonance coupling displacement, and reasonably explain the gas-water distribution and production pattern of deep reservoirs in the Xujiaweizi fault depression of the Songliao Basin and tight gas reservoirs in the Linxing-Huangfu area of the Ordos Basin.

基于变分模态分解的米兰科维奇旋回划分厚层砂砾岩地层层序的方法及其应用

在利用常规测井曲线对厚层砂砾岩储层进行层序细分的过程中,存在界面不清楚、划分标准难以确定的问题,而米兰科维奇旋回作为沉积地层中的一种重要地质事件,在漫长的地质历史时期中具有相对的稳定性,这种特性使得在米氏旋回约束下的层序划分具有更高统一性。利用变分模态分解(VMD)方法对松辽盆地徐家围子断陷营城组四段(营四段)厚层砂砾岩地层中米兰科维奇旋回进行时频分析,提取与米兰科维奇天文周期对应的高频分量,从而实现层序的划分。结果表明:使用变分模态分解(VMD)方法对测井曲线进行处理,对研究区自然伽马曲线进行VMD分解可得到若干个特征分量,通过对比,100 ka周期对应IMF1分量;根据IMF1曲线形态并结合岩性将营四段细分为21个五级层序,并将其组合为6个四级层序,在四级层序界面处,曲线形态发生明显的突变,表现出明显的周期振荡并且有较大的响应幅度。VMD方法在营四段的应用表明,此方法能够对不同尺度的米兰科维奇旋回进行精准识别和划分,并具有较高的精度和可重复性,研究成果可用于砂砾岩地层的高频层序划分。

松辽盆地徐家围子地区深层异常压力分布及其成因

松辽盆地徐家围子地区深层蕴藏着丰富的天然气资源。天然气的生成、运移和聚集与流体压力之间存在着密切关系。异常高压是由烃的生成、差异压实以及粘土矿物的转化等因素共同作用而导致。异常低压则主要归因于地层的抬升剥蚀和流体的运移。

松辽盆地营城组火山机构-岩相带的地震响应

松辽盆地徐家围子断陷多期次喷发的火山岩在纵向和横向上相互叠置,造成火山岩地震响应特征复杂,影响了对火山岩储层的地震预测精度和地质规律的认识.本文基于钻井和连片三维地震资料,结合区域构造认识,建立了徐家围子断陷营城组火山机构-岩相带的地震响应模式,并利用相干体和地层切片等属性分析技术实现了火山机构岩相带的空间识别.从火山口到远源相带火山岩体非均质性减弱,在三维相干体切片上表现为相干属性变化率的降低.研究区主要发育四种火山机构-岩相带,其地震响应特征分别为,①火山口穹窿多种岩相迭合相带:表现为杂乱反射带、自下而上呈放射状、围绕火山喷口厚度向外减薄、相干性强、剖面和平面形态多变;②近源爆发相与溢流相叠置相带:具有断续层状、中强振幅、低频反射特征,呈环带状围绕火口中心相带分布;③远源爆发相带:火山机构一侧具有上拱的板状外形,表现为楔形层状连续中强振幅反射特征;④远源火山沉积相带:具有板状外形,亚平行反射结构,能量较强和同相轴连续的响应特征.这些反射特征是火山作用喷出物堆积过程中,内部层结构和层形态呈规律性变化的地震表象.

徐家围子地区火山岩储层特征研究

为识别徐家围子地区火山岩微相类型 ,研究火山岩储层的微观结构特征、储层类型及储层参数 ,以岩心资料、试气成果、测井资料为基础 ,对火山岩储层特征进行了深入研究。其结果 :本区火山岩储层可划分为流纹岩、安山岩两类 ;建立了不同类型储层的有效孔隙度计算方法和有效厚度划分标准。这一成果对本区火山岩气藏的勘探开发具有一定的指导作用。

徐家围子断陷构造地质特征研究新进展

在徐家围子断陷深层连片三维地震精细解释的基础上,结合前人的研究成果,系统的刻画了深大断裂的性质、产状和时空分布规律。从区域构造应力场着手,详细剖析了徐家围子断陷的构造地质特征,重新构建了深大断裂体系。依据剖面特征和断陷的地质结构,首次在徐家围子断陷内解释出两条深大走滑断裂带,发现深大走滑断裂控制了营城组火山岩的形成和分布。明确了徐家围子断陷"两凹夹一隆、东西分带、南北分块"构造格局的动态演化过程及其控制因素。详细剖析了断陷期地层的沉积发育过程、后期改造过程以及现今赋存特征。为庆深气田火山岩储层分布规律预测奠定了基础。

徐家围子断陷火山岩储层特征及演化规律

储层物性是影响徐家围子断陷火山岩气田天然气聚集的重要因素,理清火山岩储层物性特征及影响因素将有利于指导该区深层火山岩的勘探部署工作。通过岩心、岩屑以及显微结构观测,深入分析了火山岩储层的岩石学特征和储集空间特征,初步探讨了徐家围子断陷营城组火山岩储层的储集空间类型及其演化规律。研究结果表明,徐家围子断陷营城组火山岩储层的储集空间主要有原生孔隙、次生孔隙及裂隙3类,不同的储集空间类型发育部位不同;储集空间的发育受到岩性与岩相的联合控制,喷溢相上部亚相的气孔流纹岩、爆发相热碎屑流亚相的熔结凝灰岩、火山通道相火山颈亚相的角砾熔岩储层物性最好;原生孔隙一般连通性较差,而成岩过程中的微裂隙以及后期的构造缝改善了原生孔隙的连通性;火山岩经历了岩浆冷凝收缩、风化淋滤、有机酸溶蚀以及碳酸溶蚀等作用,形成了原生气孔、冷凝收缩缝、脱玻化孔、长石溶孔、火山灰溶孔等大量的储集空间;构造裂隙与地下流体充注的耦合关系影响着储层的溶蚀作用。

松辽盆地庆深气田深层火山岩储层储集性控制因素研究

松辽盆地庆深气田深层火山岩主要岩石类型为流纹岩、熔结凝灰岩、凝灰岩、火山集块岩、安山岩、英安岩和粗面岩,以中酸性火山岩为主,其主要储气岩为流纹岩和凝灰岩,与国内其他含油气盆地的火山岩储层明显不同。其原生孔隙受岩性、岩相控制,后期的成岩改造作用,包括构造活动、风化淋滤、溶蚀作用、脱玻化作用决定了火山岩次生孔隙发育程度,尤其是溶蚀作用,它是决定原生孔隙不发育火山岩能否成为有效储层的关键因素。不同地区火山岩储层的发育状况与火山岩所处的位置有关。火山机构多沿断裂带分布,火山口附近多种岩相叠合区和近火山口爆发相和喷溢相叠合区的储层物性较好,是天然气勘探的有利目标。