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.

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.

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.

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.

Present geotemperature and its suggestion to natural gas generation in Xujiaweizi fault-depression of the northern Songliao Basin

According to stastistic of present geotemperatures at the depths of 1000,2000,3000 and 4000 m,respectively in the Xujiaweizi fault-depression of the north Songliao Basin,the result indicates that Xujiaweizi fault-depression falls in the high geotemperature area,with the higher geothermal gradient in the depression layer than that in the fault-depression layer.The geothermal gradient decreases with the increasing of the depth.The thermal conductivity of rock greatly controls the geothermal gradient.The main factors constraining the current geotemperature include thermal configuration of the earth's crust, deep faults,distribution and abundance of radioelements.The high geotemperature is in favour of generation of deep gas.

Experimental Insights on the Structural Patterns and Their Formation Mechanisms of the Xujiaweizi Fault Depression in the Songliao Basin

The Xujiaweizi （XJWZ） fault depression is a primary area for deep-seated gas explo- ration in Daqing. Through seismic profile interpretation, the main sag-controlling fault and struc- tural characteristics in the XJWZ fault depression were analyzed based on folds and faults analysis. A three-dimensional geological model of the XJWZ fault depression was also set up to enable fur- ther discussion by means of structural physical modeling. According to our research, the basic structural framework of the XJWZ fault depression was the result of regional extension. Its forma- tion and evolution were mainly controlled by the Xuxi fault. The structural framework of S-N blocking was due to changes in the fracture attitude. The Xuzhong uplift and the depressions on both sides belong to a normal-fault-related fold and were formed by controlling of the ramp/flat normal fault in the same tectonic movement period.

徐家围子断陷沙河子组煤岩气成藏条件及突破方向

为明确徐家围子断陷煤岩气勘探有利区,综合地震、岩心和地球化学等多种资料,系统分析了煤岩气成因、烃源岩类型、储层特征和储盖组合等有利成藏条件。结果表明:(1)沙河子组1号、2号煤层是形成于三角洲前缘和滨浅湖沼泽环境的稳定煤岩,煤岩厚度为3~10m,TOC平均约为29.65%,正处于高—过成熟阶段;(2)沙河子组煤层气以甲烷为主,为自生自储的高—过成熟煤型气;(3)煤岩储集空间类型多样,以张性微裂隙、原生植物组织孔、气孔和矿物质孔为主,孔隙度和渗透率分别平均为4.74%和4.42mD,是深层有利储层;(4)沙河子组顶部发育泥岩、泥质粉砂岩2种盖层和3种储盖组合,顶底泥岩型和顶泥底砂型储盖组合封闭性高,与煤层内广泛分布的超压封存箱一起,为煤岩气的保存创造了有利条件;(5)在煤层气藏地质特征研究基础上,通过生烃模拟估算研究区各生烃洼槽的资源量,并结合煤岩厚度、埋藏深度、成熟度等多种参数,优选宋站洼槽1号煤层和徐西洼槽2号煤层2个有利区,泥质盖层厚度大于5m的区域为近期煤层气勘探突破方向。

松辽盆地徐家围子断陷沙河子组沉积相类型及演化模式

【目的】徐家围子断陷沙河子组致密砂砾岩储层具有非常大的天然气勘探潜力,有望成为大庆油田深层火山岩气藏勘探的重点接替领域。【方法】综合运用岩心、录井、测井及地震等资料,对徐家围子断陷沙河子组沉积相展布及沉积演化模式开展了研究。【结果与结论】徐家围子断陷沙河子组发育辫状河三角洲、扇三角洲、具供给水道的远岸浊积扇、近岸水下扇、扇三角洲前端滑塌浊积扇以及浅湖—半深湖、深湖相等沉积相。安达凹陷、徐东凹陷以及肇州凹陷东侧的缓坡带接受来自肇东—朝阳沟基底古隆起的碎屑物质而发育辫状河三角洲沉积,局部发育由远源供给水道形成的湖底浊积扇沉积体;安达凹陷、徐东凹陷、徐西凹陷以及肇州凹陷西侧等徐西陡坡带接受来自中央隆起带粗碎屑物而发育扇三角洲沉积体系,以近源短流为基本特征,局部发育近岸水下扇沉积,且由于湖盆边缘发育的扇三角洲沉积体不稳定,在扇三角洲沉积体前方形成滑塌浊积扇沉积。

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。

不同构造单元油水分布规律及其主控因素研究

由于葡萄花油层各构造单元油水分布复杂,为了掌握徐家围子向斜区的油水分布规律,在对研究区构造单元精细划分的基础上,分析不同构造单元的油水分布及主控因素。研究发现,研究区可分为3个构造单元,油水分布主要呈现为上油下水,各构造单元油水富集层位不同,主要因为其在油藏成因上有所差异:(1)洼槽区主要为反向源断裂充注,由弱-双强两种充注模式为其供烃,且圈闭由断层及断层与岩性共同作用形成;(2)南部斜坡区主要为反屋脊源断裂充注;(3)北部斜坡区为屋脊源断裂及反向源断裂充注。斜坡区主要为强充注模式,且圈闭主要以构造作用形成。该研究结果对认识不同构造单元的油气成藏规律以及指导油气勘探具有参考意义。

松辽盆地北部徐家围子断陷火山岩分布及天然气富集规律

提出一个新的带通滤波器———延拓回返垂直二次导数,该滤波器可通过调节延拓回返高度及次数来达到调频目的,以突出勘探目标层段的信息.利用该技术对松辽盆地深层勘探程度最高的徐家围子断陷的航磁资料进行目标处理,与钻井资料对比表明,经处理后的航磁资料可以较好地反映火山岩的分布特征.以航磁资料为主结合钻井、地震资料预测了徐家围子三套火山岩的平面分布.指出航磁异常梯度带是火山岩储层的发育区带,近烃源岩或沟通烃源岩的航磁异常梯度带是火山岩天然气的富集区带.该认识对今后松辽盆地的勘探部署有着十分重要的指导意义,对我国其他地区的火山岩勘探也具有借鉴意义.

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.

徐家围子断陷深层天然气盖层特征及封盖性评价

利用钻井、测井和分析测试资料,结合天然气气藏剖面可知:徐家围子断陷共发育两种类型盖层,即泥岩和火山岩。通过对徐家围子断陷深层天然气盖层识别标志、分布、封闭能力及对天然气成藏与分布控制作用的分析表明:徐家围子断陷深层天然气发育泉一、二段,登二段两套区域性盖层;营一段顶部局部性盖层和营一段、三段内的隔层。区域性盖层和局部性盖层分布范围广、厚度大、排替压力较高、封闭能力强,控制着徐家围子断陷深层天然气的区域聚集与分布;隔夹层分布范围小、厚度薄、排替压力低、封闭能力弱,仅控制着天然气在储集层中的局部聚集与分布。

松辽盆地徐家围子断陷火山岩内断层侧向封闭性及与天然气成藏

松辽盆地北部徐家围子断陷深层指泉头组一、二段以下地层,发育3套火山岩储集层:即火石岭组、营城组一段和营城组三段,目前在营城组两套火山岩中发现了规模较大的天然气藏。徐家围子断陷断裂系统复杂,对天然气成藏控制作用明显,控藏的断裂为早期控制火山裂隙式喷发,在泉头组沉积晚期—青山口组沉积早期强烈活动,同时在区域性盖层段具有顶部封闭能力的断裂,断裂形成时为火山通道,没形成明显的断层面,泉头组沉积晚期—青山口组沉积早期断裂活动形成断层角砾岩带,天然气沿断裂大规模垂向运移,聚集在营城组火山岩中,由于断层角砾岩带侧向封闭能力较差,侧向受营城组四段物性较低的砾岩遮挡聚集成藏,对于正断层而言主要聚集在下盘,逆断层主要聚集在上盘。徐中走滑断裂为主要的控藏断裂,由于倾向和断层性质(正和逆)的改变,天然气在两盘聚集具有"此消彼长"的特征,天然气这种聚集规律对于勘探部署、确定气藏的边界和提交储量具有重要的指导意义。

徐家围子断陷深层结构形成与演化的探讨

徐家围子断陷是松辽盆地北部深层最重要的含气断陷。本文根据最新地震和钻井资料综合研究成果,结合前人研究认识,探讨了徐家围子断陷的形成与演化,认为徐家围子断陷在区域构造位置上处于东北地区松辽盆地的北部,处于松辽盆地区域莫霍面隆起的西斜坡上,特定的位置决定了其形成演化的各个阶段受东北地区区域板块构造运动的控制,与松辽盆地的形成与演化具有一定的关系。徐家围子断陷形成与演化可以划分为5个阶段,是太平洋构造域板块间的相互作用和深部热力作用发育演化的结果,这种过程造就了现今南北分块、东西分带、凹隆相间、构造复杂和沉积岩与火山岩并存的地质结构。徐家围子断陷深层现今构造格局受控于近NW向的徐中断裂、近SN向的徐西断裂、近NW向的徐东断裂带和四组近NE向的断裂。本次研究,对以往无法解释的很多地质现象给予了很好的解释,得出了一些崭新的认识,也从宏观上为寻找天然气资源给予了有力指导。

徐家围子断陷营城组火山岩分布特征及火山喷发机制的新认识

基于深层钻井和连片处理三维地震资料,结合同位素测年,本文对松辽盆地北部徐家围子断陷白垩系营城组火山岩的分布特征及其喷发机制进行了研究。本区火山岩分布广、厚度大、沿深大断裂串珠状分布;纵向上分为下部营一段和上部营三段两套;营一段分布于断陷中部及其以南地区,岩性以酸性为主;营三段分布于断陷中部及其以北地区,酸性和中、基性火山岩均有发育。本区断裂类型及其组合复杂,正、逆、走滑和花状断裂都有发育;两组断裂交汇部位是火山喷发的主要通道。深大断裂与火山岩时空展布关系显示,营一段火山岩主要受徐中断裂控制,由北向南依次喷发,岩性以酸性为主;营三段火山岩主要沿着徐东花状断裂带由南向北依次喷发,表现为基性与酸性交替的双峰式。营城组火山岩喷发类型有三种:裂隙式、中心式与复合式。徐家围子断陷营城组火山岩储集性能优良且毗邻烃源岩,与断裂、源岩及盖层有利匹配,可构成有利的生储盖组合,具有良好的天然气勘探前景。

徐家围子断陷火山岩岩性的测井识别技术

本文以钻井取心、分析测试和测井资料为基础,应用聚类分析方法,通过各种测井交会图在大庆油田徐家围子断陷营城组深层火山岩中识别出了六类岩性,与钻井和录井资料解释结果相比,判别正确率达90％以上。该技术对于在未取心井中正确识别火山岩老性具有重要意义,也为火山岩储层评价研究奠定了良好的基础。