延安南部延长组长9段顶部页岩是一套重要的烃源岩,为探讨富有机质页岩的形成条件及发育模式,对长9段顶部的露头剖面及岩心进行古沉积环境分析.结果表明,长9段顶部页岩中的CaO/(MgO·Al2O3)均值为 0.116,V/(V+Ni)均值为 0.75,δU 均值为 0.85,Sr/Ba 均值为 0.34,Sr 含量＜300×10-6,指示研究区长9段顶部页岩沉积期为温暖、湿润的气候,水体为淡水-微咸水环境,为弱还原性.估算得出古水深为20.6～58.3 m,古湖泊生产力为963.1～1 251.4 g/m2a,表明页岩主要发育在古湖泊生产力较高的浅湖-半深湖环境.适宜的气候、足够的水深以及火山活动,导致长9段晚期有机质大量富集,形成了一套有机质含量高、厚度大的黑色页岩,同时为长8段致密油成藏奠定了基础.

塔里木盆地柯探1井和轮探1井相继在下寒武统吾松格尔组获得高产工业油气流,突破了整体富泥的传统层系评价定位,但目前对吾松格尔组岩相古地理研究几乎为空白,制约了有利储集相带评价与预测.综合利用阿克苏地区露头资料、录井岩屑、C/O同位素曲线、测井及地震资料,分析了塔里木盆地吾松格尔组沉积期古地理格局、沉积环境及储层分布.结果表明:①吾松格尔组沉积期沉积充填序列及地层分布受塔南、乌恰及温宿三大台内古隆和边缘凹陷控制.古隆起区吾松格尔组超覆沉积,厚度薄,发育混积潮坪、弱镶边台地相;边缘凹陷地层齐全、厚度大,发育深水盆地相和局限潟湖相.②吾松格尔组沉积序列总体表现为一个完整的"海侵—海退"沉积旋回,轮南至古城地区超覆发育塔里木盆地寒武系第一套弱镶边型台地边缘,联合控制沉积期混积潮坪—局限台地的发育.③吾松格尔组发育台缘丘滩、礁后滩及潮上—潮间带薄层台内滩3类白云岩储集层,分布面积大.其中,主要发育于轮南—古城地区的台缘丘滩和礁后滩白云岩储层品质较高,预测面积达12070 km2.以储集层预测为基础,评价认为轮南—古城地区与上覆膏盐岩盖层构成新的一套有利储盖组合且轮探1井已获突破,是下一步重点探索的有利区带.

为识别塔河油田奥陶系中深部岩溶发育模式,进一步寻找油气勘探有利区,根据Klimchouk(2006)基于深成(上升型)洞穴作用所建立的水力地层单元格架,结合塔河南部覆盖区一间房组基质孔隙性储层的发育特征(上部含水层),上寒武统下丘里塔格群基质孔隙型结晶白云岩的发育(下部含水层),构建了南部覆盖区的宏观区域性水力地层格架;并认为其位于含水层内部的次一级水力地层格架内,类似于弗罗里达东南部的更新世Biscayne含水层.初步建立了塔河南部加里东中期Ⅱ～Ⅲ幕或海西早期承压环境下的岩溶分布模式,南部承压区由南向北可以进一步分成大气淡水承压岩溶作用带和沿断裂大气淡水/盆地卤水混合承压岩溶作用带.

鄂尔多斯盆地子北油田长6储层为特低渗透致密砂岩,孔隙结构复杂,非均质性强,需压裂才能出油,无纯油层,产油层都为油水同出,产油量低、含水率普遍较高.以往有效厚度解释主要研究区分油水层、水层,但按探明储量计算要求,油水层产油量如达不到储量起算标准就不能确定为有效厚度.开展了有效油水层解释综合研究,将油水层解释类别细分为有效油水层、低效油水层,确定合试层测井资料选用办法,规范储层测井资料读值方法,研制并确定有效油水层解释标准.实际应用表明,它们提高了特低渗透致油水层的有效厚度解释精度,对类似复杂地质条件的油藏研究具有借鉴意义.

前人认为银额盆地下白垩统物源主要来自凹陷周缘的造山带或凸起区,但对于下白垩统的物源具体属于何套地层、确切源区位置等问题,并未开展过相关研究.笔者以哈日凹陷为例,通过对该凹陷下白垩统8个沉积岩样品开展地球化学和碎屑锆石U-Pb年代学研究,以期解决以上问题.研究结果表明:(1)碎屑锆石按年龄可以分为三叠纪锆石、二叠纪锆石、石炭纪锆石和古老锆石4类,对应的年龄分别为237.9±3.2～238.3±8.4Ma、255.0-+9.7～285.9+4.3 Ma、307.0±23.0～ 330.0±3.0Ma和434.0±4.0～2584.0±14.0 Ma.(2)微量元素和锆石年龄组成特征表明,下白垩统以二叠系和石炭系物源供给为主,包括二叠纪和石炭纪侵入岩和沉积岩.(3)锆石年龄分布指示哈日凹陷下白垩统物源具有多源区的特征,凹陷西北部的洪格尔吉山、南部的宗乃山和东部的切刀山对其均有物源贡献.(4)3个物源区对巴音戈壁组和苏红图组的物源贡献率具有一定的差异,如宗乃山地区对苏红图组有较大的物源贡献率,这种差异可能由沉积物迁移距离、源区地质体剥蚀速率、构造运动等原因所致.下白垩统物源特征的确定,对于恢复哈日凹陷早白垩世原型盆地、建立早白垩世沉积古地理模型等均具有重要的意义.

Ganquan-Fuxian area is a main enrichment area of tight oil in Yanchang Oilfield,Ordos Basin,however, the resource potential and enrichment law are unclear,and the exploitation risk is large. The data of cores and log-ging were used to study the distribution of Chang 7 source rocks,and the total organic carbon,pyrolysis,chloro-form bitumen"A"and vitrinite reflectance(Ro)were analyzed to evaluate the hydrocarbon-generating potentials of Chang 7 source rocks. The results show that the organic matter is mainly of Ⅰ and Ⅱ1 type and in a matu-rate oil generation stage,with great hydrocarbon-generating potential,which is determined to be relatively good source rocks. The thickness and organic matter abundance of Chang 7 source rocks are controlled by sedimentary environment. The Chang 7 source rocks are mainly distributed in northwestern deep to semi-deep lake sedimentary area near the center of the lake basin,with the thickness of 50-70 m,which can be the key area for the next tight oil exploration. The research result is helpful for guiding the evaluation of hydrocarbon geochemical characteris-tics and hydrocarbon generation potential and the prediction of favorable oil and gas areas.

借助丰富的岩心物性分析、铸体薄片、压汞、扫描电镜、阴极发光等资料,对研究区的储层特征进行了分析,长8油层组储层主要以长石砂岩为主,其次为岩屑质长石砂岩.砂岩碎屑成分以长石为主,其次为云母、石英以及各类岩屑和少量的重矿物,分选较好.胶结物以碳酸盐胶结物为主,其次是粘土胶结、以及少量的硅质和铁质胶结.研究区长8油层组为特低孔、特低渗储层,次生孔隙较为发育.沉积作用是研究区储层物性的主要因素.此外成岩作用对储层物性也有一定的影响.研究区储层有利的成岩作用主要有溶蚀作用,而胶结作用、压实作用等会使储层的孔隙降低,储层物性变差.

为了明确鄂尔多斯盆地南部三叠系延长组储集层分带特征,利用锆石同位素测年、储层微观分析方法研究盆地南部三叠系延长组储层分布特征.研究结果表明:盆地南部延长组储层具有明显的分区性,可分为北物源区、混源区和南物源区3个区域.从北物源区—混源区·南物源区,长石含量逐渐降低、石英含量逐渐增高.北物源区岩屑和变质岩屑含量中等;混源区的沉积岩屑含量最高,变质岩屑含量最低;南物源区沉积岩屑含量最低,变质岩屑含量最高.填隙物中,方解石胶结物在北物源区含量最高,南物源区含量最低;水云母在混源区含量最高,北物源区含量最低;绿泥石在混源区含量最高,在南物源区含量最低.北物源区颗粒分选性较好,南物源区分选性整体较差;磨圆度混源区最好,南物源区最差.物性分布特征上,北物源区、混源区、南物源区孔隙度、渗透率大小整体呈“V”字形分布,北物源区和南物源区整体较高,混源区较低.

储层”四性”关系研究是指对储集层的岩性、物性、电性及含油性特征进行分析,并对其相互间关系研究,此项工作是储层流体识别、储量参数计算、试油试采、选层选段的基础.鄂尔多斯盆地是一个大型中生代内陆坳陷型盆地,油气资源丰富[1-2].郑寨子地区位于鄂尔多斯盆地中部,行政区划属陕西省榆林市旬定边县东勘探面积约600多平方公里,目前开发层系包括长8、长6、延10、延8等,主力产层长6-1发育低阻油层,具有较好的勘探潜力,对该地区开展储层四性关系分析尤其是低阻油层识别具有重要的意义,这将为该区进一步开发评价和增储增产,提供了有力依据[8-13].因延8等层试油仅个别井出油,动态及岩心数据较少,目前不足以支撑储层四性分析及流体识别等研究,本次研究重点是对目标区长6低阻储层四性关系及其流体识别方法进行了研究.

综合分析鄂尔多斯盆地南部延长探区的岩心、测井、铸体薄片、扫描电镜、阴极发光、X衍射、压汞分析等资料,对研究区长8油层组储层特征以及影响因素进行研究.结果表明长8油层组主要为长石砂岩和岩屑长石砂岩,成分成熟度低、结构成熟度中等;储层孔隙类型多样,粒间孔和长石溶孔为主要的储集空间,喉道类型以小孔微喉型为主;物性特点为典型的低孔低渗储层;储层明显受沉积相和成岩作用的综合影响.最有利的沉积微相为沉积厚度大、粒度较粗的水下分流河道微相;同时,建设性及破坏性成岩作用对储层物性改造具有双重作用,建设性成岩作用由于溶蚀作用使得物性变好,而破坏性成岩作用由于胶结及压实致使物性变差.

We studied the distribution and main controlling factors of the reservoirs of the Yanchang formation in the Xuyi area, southern Ordos Basin. The results showed that the reservoir is a typical lithologic reservoir, with the characteristics of poor connectivity and strong heterogeneity. The reservoir is mainly distributed in the plane underwater distributary channel and mouth bar sand, longitudinally developing 7 sets of oil-bearing strata. The formation and accumulation of reservoir were mainly controlled by oil source conditions, change of sedimentary microfacies and reservoir properties, tectonic uplift nose and fractures.

Youshashan oilfield is a typical complex fault block reservoir; this kind of reservoirs have a lot of characteristics, such as complex structure, loosely scattered oil sand bodies, and difficulty in developing fault block reservoir. In this paper, based on geology, logging and developing dynamic data, distribution and controlling factors of oil sand bodies were synthetically studied. The research results not only have an important practical significance for future perfection of injection-production of the reservoir and improving waterflooding production of blocks, but also provide corresponding reference for exploration and development of the same type of reservoirs.

Because the geographical statistics cannot be used in the sparse well net area for the reservoir bed modeling of high accuracy,the paper proposes the modeling thinking of reservoir bed based on taking seismic data as constraint condition.The modeling,depending mainly on the three dimensional seismic explanation information and the prediction results of seismic inversion restricted by logging reconstruction,predicts the distribution of the reservoir sand in the well and the variation law for the physical properties of the reservoir bed to build the three dimensional model of the reservoir bed under the constraint of the prediction results by means of random modeling.This model can help to reach the required accuracy degree at the oil and gas field development stage through the onsite check,meanwhile,and provides a very good reference to the precise evaluation for the reservoir bed in the sparse well net area.

According to the comprehensive analysis on the logging data,well logging data,and well cores testing data of 120 wells and the seismic facies of 25000 kilometers long two-dimensional seismic sections of Tabei Area at the same time,the following conclusions are able to draw from.Six sedimentary facies have developed in Jurassic in Tabei Area;they are alluvial fan,braid river,braid river delta,fan delta,littoral-shallow lake,and half-deep lake.Among of them,the braid river delta and fan delta have most widely developed.The braid river deltas have mainly distributed in the area of Yingmaili,Donghetang,Yuenan,western of Lungu,Hadexun,and the southern area of Caohu and Juema.The fan deltas have mainly distributed in the areas of Lunnan and Caohu.The braid rivers have mainly distributed in the areas of Mana 1-Mana 3-Yingmai 3-Yuenan 1-Hade well blocks,Yingmai 6 well block,and southeast of Tabei Area.Littoral-shallow lake and half-deep lake have mainly distributed in Qunkeer Area.The alluvial fan has mainly distributed in the west part of Mana 3 well block and mountain front zones of Kuqa depression.According to the analysis,the aquatic bifurcating channels and subquatic distributary channels of the braid river delta,the bifurcating channels of the fan delta plain,braid river channel sandbody,and the turbinate sandbody located in eastern part of the Tabei Area are the prospective objects for finding lithologic trap.

Through the fine analysis of sedimentary facies,the microfacies proportion of different sand bodies is analyzed.The reservoirs in Beisanxi Area of Saertu Oilfield are divided into four reservoir structures:Type A and Type B,which are mainly distributary channel facies;Type C and Type D,which are mainly sheet sand of delta front.The geologic model is established using the geologic constrain modeling method.In a small layer for unit,the reserves of different microfacies are calculated and reserves distributions are analyzed,which shows that the reserves distribution of reservoir with different facies structure have different features and the reserves structures are different.On basis of traditional reserves estimation and considering the influence factors of facies structure on reserves control,this paper also considers that this method can directly represent the reserves of different genetic sand bodies and can provide a quantitative basis for analyzing the potentialities of different sand bodies.