The saline lacustrine hybrid sedimentary rocks are complex in lithology and unknown for their sedimentary mechanisms. The hybrid sedimentary rocks samples from the Neogene upper Ganchaigou Formation to lower Youshashan Formation (N1-N21) in the Fengxi area Qaidam Basin, were investigated through core-log and petrology-geochemistry cross-analysis by using the core, casting thin section, scanning electron microscope, X-ray diffraction, logging, and carbon/oxygen isotopic data. The hybrid sedimentary rocks in the Fengxi area, including terrigenous clastic rock and lacustrine carbonate rock, were deposited in a shallow lake environment far from the source, or occasionally in a semi-deep lake environment, with 5 lithofacies types and 6 microfacies types recognized. Stable carbon and oxygen isotopic compositions reveal that the formation of sedimentary cycles is controlled by a climate-driven compensation-undercompensation cyclic mechanism. A sedimentary cycle model of hybrid sedimentary rocks in an arid and saline setting is proposed. According to this model, in the compensation period, the lake level rises sharply, and microfacies such as mud flat, sand-mud flat and beach are developed, with physical subsidence as the dominant sedimentary mechanism; in the undercompensation period, the lake level falls slowly, and microfacies such as lime-mud flat, lime-dolomite flat and algal mound/mat are developed, with chemical-biological process as the dominant sedimentary mechanism. In the saline lacustrine sedimentary system, lacustrine carbonate rock is mainly formed along with regression, the facies change is not interpreted by the accommodation believed traditionally, but controlled by the temporary fluctuation of lake water chemistry caused by climate change. The research results update the interpreted high-resolution sequence model and genesis of hybrid sedimentary rocks in the saline lacustrine basin and provide a valuable guidance for exploring unconventional hydrocarbons of saline lacustrine facies.

This paper examines the enrichment conditions of deep natural gas reservoirs in the Qaidam Basin and delineates the exploration potential utilizing seismic, geological, geochemical, well-logging, and drilling data. The findings indicate the presence of two high-quality gas source formations, namely the Jurassic and Paleogene formations, along the northern margin and the western part of the basin, respectively. The formations both exhibit advanced evolution and robust gas-generating capacity. The deep layers along the northern margin consist of bedrocks and Paleogene clastic reservoirs, while the western deep layers feature Paleogene lacustrine carbonate reservoirs. The reservoirs west of Qaidam Basin are widely distributed on the plane and vertically form multiple reservoir cap combinations. The primary pores, dissolution pores, fractures, and other pore types developed in the reservoirs are considered as the storage space for deep gas accumulation. The continuous active deep faults serve as high-quality channels for deep gas sources; furthermore, the formation of deep structures is well-matched with natural gas generation. The deep hydrocarbon source rocks in the western Qaidam Basin are characterized by early and continuous hydrocarbon generation. Early-generated liquid hydrocarbons undergo high-temperature cracking into gas during later burial, resulting in a robust gas-generating capacity and significant potential for deep resources. The widely developed salt rocks, argillaceous rock, and abnormally high-pressure layers in the deep Qaidam Basin contribute to preserving deep natural gas. In conclusion, it is believed that deep gas reservoirs in the Qaidam Basin are enriched in the traps around hydrocarbon-generating sags with developed faults. Key favorable areas for deep-seated natural gas exploration include the basement rocks of the ancient piedmont uplift in the northern margin of Qaidam, the Paleogene clastic rocks in the central structural belt, and the carbonate rocks along the Yingxiongling structural belt in the western part of the basin.

Lacustrine carbonate reservoirs, extensively distributed in China, have extensive oil and gas exploration potential. However, such reservoirs are characterized by high content of terrigenous debris and complex lithofacies, and the resultant high difficulty in lithofacies identification severely restrains exploration expansion and efficient development, especially for the Upper Member of the Paleogene Lower Ganchaigou Formation (E32) of the Yingxi area in the Qaidam Basin, with burial depths generally greater than 4000 m. This research targets this area and develops a methodology for detailed lithofacies identification, after systematically investigating the characteristics of lithofacies and well log responses of lacustrine carbonate rocks, on the basis of a massive volume of data of cores, thin sections, and experiments of the study area. The analysis identified lithofacies in the Upper Member of the Paleogene Lower Ganchaigou Formation of the Yingxi area, namely, pack-wackestone, mudstone, laminated carbonate, muddy gypsum, and limy claystone. The analysis of well log response characteristics suggested that natural gamma ray, matrix density, and bulk density were sensitive to lithofacies. Then, for the first time, the rock fabric factor (RFF) method was proposed, and the lithofacies identification plot was based on the calculated RFF and high-definition spectroscopy log. The presented methodology was applied to 55 wells in the study area. The average accuracy of lithofacies interpretation in 14 cored wells reached 82.4%, indicating good application performance. This method improves the lithofacies identification accuracy of lacustrine carbonate rocks, which is of great significance for investigating the reservoir distribution law and guiding exploration and development.

我国湖相碳酸盐岩储层分布广泛,具有极大的油气勘探前景.但该类储层陆源碎屑含量高、岩相种类多,导致岩相识别困难且严重制约了该领域勘探拓展和高效开发,这在埋藏深度普遍大于4000m的柴达木盆地英西地区古近系下干柴沟组上段(E32)尤为典型.以英西地区为例,充分利用区内大量岩心、薄片和实验分析资料,系统分析湖相碳酸盐岩岩相特征及测井响应特征,并建立了识别方法和图版.分析结果表明,英西地区E32发育颗粒灰云岩、泥晶灰云岩、纹层状灰云岩、泥质膏岩和灰云质泥岩等5种类型的岩相.基于测井响应特征分析,确定自然伽马、骨架密度、体积密度为岩相识别敏感参数,进而首次提出岩石结构因子(RFF)技术;利用计算得到的RFF参数,结合元素测井资料建立了岩相识别图版,将其应用于研究区48口井,在12口取心井中岩相解释平均符合率达到80.2％,应用效果较好.岩石结构因子技术提高了湖相碳酸盐岩岩相识别符合率,对研究储层分布规律、指导勘探开发具重要意义.

Based on the data of field outcrops, drilling cores, casting thin sections, well logging interpretation, oil/gas shows during drilling, and oil/gas testing results, and combined with modern salt-lake sediments in the Qinghai Lake, the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics, development patterns, sand control factors, and hydrocarbon accumulation characteristics. Beach-bar sand bodies are widely developed in the Neogene saline lake basin, and they are lithologically fine sandstone and siltstone, with wavy bedding, low-angle cross bedding, and lenticular-vein bedding. In view of spatial-temporal distribution, the beach-bar sand bodies are stacked in multiple stages vertically, migratory laterally, and extensive and continuous in NW-SE trending pattern in the plane. The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km(2). The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone, and the debris input from the source area affects the scale and enrichment of beach-bar sandstone. The ancient landform controls the morphology and stacking style of beach-bar sandstone, and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone. The beach-bars have a reservoir-forming feature of "one reservoir in one sand body", with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction. Three favorable exploration target zones in Zhahaquan, Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.

The purpose of this paper is to determine the provenance of Paleogene clastic rocks in Shaxi region and its relationship with neighbouring area, including Gasi region, Yuejin region, Hongliuquan region, Qigequan region by referring to such factors as regional geological settings, heavy mineral assemblage, heavy mineral stabe coefficient, rare earth element(REE) geochemistry, and sand body geometry. The results show that the heavy mineral assemblages and REE patterns in the three regions of Shaxi, Gasi and Yuejin are similar, and they are quite different from those of Hongliuquan and Qigequan region whose sources are definitely from the Altun mountains nearby. In addition, plane distribution of heavy mineral stability coefficient and single sand bodies distribution are mapped out that the palaeocurrent direction of Shaxi region is SW-NE. The results of the present work implied that the provenance of Paleogene clastic rocks in Shaxi region comes from Tiemulike palaeomountains to the southwest.

To identify the developmental characteristics and controlling factors of the beach‐bar sandstone in saline lake basins in the Qaidam Basin, China, the lithology and bedding structure of some representative outcrops of the Neogene saline lake basins were comprehensively investigated by means of experimental test data of local drilling cores, casting thin sections, and grain size, together with field outcrops in the basin and the modern salt lake deposition record of Qinghai Lake. Two types of sand bodies in the saline lake basins, that is, delta sand bodies and shore‐shallow lake beach‐bar facies were revealed. Neogene saline lake basins were found to host widespread beach‐bar sand bodies. Lithologically, the sand bodies were composed of fine‐grained sandstone and siltstone, with wavy bedding, low‐angle cross‐bedding, and bimodal cross‐bedding. The beach‐bar sandstone was characterized by multi‐layer superimposition, lateral migration, and NW–SE wide‐coverage continuation. Drilling data showed that beach‐bar sand bodies extended from 10 to 35 km in width and most of them occurred 3–15 km away from braided river delta front. It has been predicted that the total area of beach‐bar sand bodies of 14 sand groups in the Neogene spread across 5,000 km2. Four factors, that is, lake water salinity, terrigenous input, palaeogeomorphology, and monsoons, controlled the construction of the beach‐bar sand bodies developed in the Neogene saline lake of the Qaidam Basin. We can conclude that the settling velocity and transport distance of the sand bodies were affected by the water body salinity in such saline lake basins. Also, the distribution range of the beach‐bar sand bodies was affected by the clastic input from a terrigenous provenance. Furthermore, the wide‐coverage distribution and local enrichment of the beach‐bar sandstone were affected by palaeogeomorphology, and the distribution direction of the beach‐bar sandstone was affected by the driving effect of NW monsoons. We propose a deposition model of the beach‐bar sandstone in saline lake basins that can predict favourable beach‐bar sand body regions, to support the major discoveries of lithologic traps in southwestern Qaidam, China.

以柴达木盆地英雄岭构造带西段(英西地区)始新统为研究对象,综合岩心、全岩X衍射、铸体薄片、阴极发光、扫描电镜、碳氧同位素、溶蚀模拟实验等测试结果,探讨湖相混积型碳酸盐岩储层的基本特征、成因机制和发育模式.结果表明:研究区储层岩矿组成以碳酸盐矿物为主,并与陆源碎屑、蒸发岩矿物和黏土矿物等混积形成混积型碳酸盐岩;按岩性可分为颗粒灰云岩、含膏灰云岩、泥晶灰云岩、纹层状灰云岩和角砾状灰云岩5种;储集空间存在孔、洞、缝等多种形式,孔径尺寸范围从纳米级到厘米级.岩性的多样性决定了储集空间具有多种尺度和多种成因,可将储层划分为白云石晶间孔型、溶蚀孔型、裂缝-角砾间孔(洞)型3类储层.晶间孔型储层形成于准同生期的白云石化作用,是咸化湖盆周期性咸化的必然结果,该类储层分布广,是湖相混积型碳酸盐岩储层的主要类型;溶蚀孔型储层是准同生期大气淡水溶解蒸发岩矿物的结果,优先发育于洼中古隆起内含膏灰云岩和颗粒灰云岩中,分布相对局限.裂缝-角砾间孔(洞)型储层为构造成因,产生于狮子沟断层沿膏盐层发生大规模逆冲、滑脱变形的过程中,呈连片分布.

Taking the mixed pre-salt carbonate rocks in the upper member of Eocene Xiaganchaigou Formation (E32) of Yingxi area in the Qaidam Basin as an example, the lithofacies and controlling mechanisms of reservoir formation are analyzed based on a large dataset of cores, thin sections and geochemical analysis. The reservoirs in E32 pre-salt layers have five types of lithofacies, of them, mixed granular calcareous dolostone, massive calcareous dolostone, plaque calcareous dolostone, and laminated dolomtic limestone are of sedimentary origin, and breccia calcareous dolostone is of tectonic origin. The four types of sedimentary lithofacies are divided into two types of saline sedimentary sequence lithofacies combinations, low-energy type in the sag area and low to high-energy type in the slope and paleo-uplift zone in the depression. Affected by high-frequency supply of continental clastic material, the two types of salty sedimentary sequences are mostly incomplete subtypes of lithofacies. Lithofacies have strong impacts on pre-salt reservoirs in E32: (1) Lithofacies type and sedimentary sequence controlled the formation and distribution of dolomite intercrystalline pores and dissolved pores during the pene-sedimentary period. (2) The structure of laminated dolomitic limestone controlled the formation of large-scale laminated fractures and high permeability channels during the diagenetic period. (3) Granular, massive, plaque calcareous dolostones have low mud content and strong brittleness, in the late tectonic reactivation period, the distribution of the three types of lithofacies, together with their distance from the top large slip faults and secondary faults, controlled the formation and distribution of high-efficiency fracture-cave brecciaed calcareous dolostone reservoirs. The above research led to the composite lithofacies-tectonic formation model of pre-salt reservoir in E32 of Yingxi area. The tempo-spatial distribution of tectonic breccia calcareous dolostone reservoirs, laminated dolomitic limestone shale oil reservoirs and granular, massive calcareous dolostone dissolved-intercrystalline pore tight reservoirs in various structural belts of the studied area have been figured out. These findings gave new insights into tight-shale oil accumulation theory in mixed carbonate successions from saline lacustrine basins, aiding in high efficient exploration and development of petroleum in the studied area.

精细刻画砂岩储层内部结构,可为柴达木盆地西部(柴西)斜坡区古近系下干柴沟组下段岩性油气藏勘探开发指明方向.以高精度层序地层学、砂体构型分析理论和方法为指导,以3D地震、钻/测井、岩心资料为基础,井震联合标定,综合分析了柴西斜坡区下干柴沟组下段层序地层发育规律与层序格架内砂体结构特点.结果表明,柴西斜坡区下干柴沟组下段整体为一个区域性湖侵序列,内部可划分为2个三级层序,4个四级层序(EMSQ1～4).下干柴沟组下段沉积期,由早至晚,A/S(可容纳空间与沉积物供给比值)持续增大,四级层序结构由向上变深的半旋回型逐渐转变为向上变浅为主、向上变深为次的非对称型.沉积相则由辫状河三角洲平原演变为前缘、滨浅湖亚相.研究区主要发育分流河道、水下分流河道、滩坝3类储层砂体,砂体叠加样式和分布规律与四级层序结构相关.三角洲平原分流河道砂体主要发育于EMSQ1中,砂体相互切割和叠置程度高,连通性好;三角洲前缘分流河道砂体主要发育于EMSQ2～3中,多呈叠加-孤立型,连通性差;滨浅湖滩坝砂体主要发育EMSQ4中,砂体呈孤立状,层内连通性佳,层间连通性差.指出现阶段岩性油气藏勘探应重点围绕EMSQ4层序内发育的滨浅湖滩坝砂体展开.

为了明确柴达木盆地新生代湖相碳酸盐岩类型特征及发育规律,利用野外露头、钻井取芯、显微结构特征等资料,按照碳酸盐岩成因分类法,对碳酸盐岩类型进行划分.结果 表明,柴达木盆地新生代发育两种成因类型碳酸盐岩储层,即生物成因和机械-化学复合成因.生物成因碳酸盐岩为藻灰/云岩类;机械-化学复合成因碳酸盐岩为颗粒灰/云岩类和泥晶灰/云岩.柴达木盆地碳酸盐岩发育颗粒滩-灰/云坪、颗粒滩(鲕粒滩)-藻丘、藻席-灰/云坪、颗粒滩-藻丘(席)-灰/云坪4种类型组合样式;灰/云坪储层在柴达木盆地西部地区大面积分布,颗粒滩储层分布于水体较浅、水动力条件相对较强的滨浅湖亚相带中,藻丘(席)分布在滨浅湖亚相内的清水、富氧环境中.

In recent years, tight oil reservoirs have been found in the upper Ganchaigou Formation (Neogene) of Zhahaquan area, Qaidam Basin, but the source rock–reservoir relationship is unclear and the favorable source rock identification and prediction method need to be built urgently. Based on the experimental data of source rock samples in the study area, it is found that there are a lot of differences between favorable and useless source rocks such as color, degree of redox, salinity, paleo-water depth, carbonate content, TOC, and sedimentary environment. Moreover, after analyzing logging responses of source rock, ΔGR and Th/U are selected to calculate TOC because the two parameters are most sensitive to organic matter abundance. Furthermore, we found that the source rocks in the shallow lake area and beach bars are longitudinally superimposed on each other, and this combination is beneficial to form high-class source rock–reservoir collocation. And, the distribution of source rocks in shallow lake area is basically parallel to the lake shoreline and is consistent with the strike of beach bars. This method can be applied to favorable source rock identification and prediction of different types of areas.

英雄岭构造带位于柴达木盆地西部地区,先后发现了狮子沟、花土沟、油砂山、英东等多个新近系油气田,是柴达木盆地石油勘探的主战场.为了拓展英雄岭构造带新近系碎屑岩岩性油气藏勘探领域,通过野外露头、钻井岩心、粒度测试等资料的综合分析,明确新近系碎屑岩发育滨浅湖滩坝、辫状河三角洲水下分流河道两种类型砂体.在湖退沉积背景下,受西部物源控制的辫状河三角洲水下分流河道砂体逐步向湖盆进积,北西—南东向斜列式分布的滨浅湖滩坝砂体向湖盆迁移;上干柴沟组辫状河三角洲水下分流道砂体发育在构造带以西地区,滩坝砂体发育在构造带西翼及核部;下油砂山组辫状河三角洲水下分流河道砂体发育在构造带西翼及核部,滩坝砂体分布在构造带核部及东翼.构造演化特征表明,新近系上干柴沟组、下油砂山组沉积时期储层砂体分布在斜坡区,而现今的英雄岭构造带为新近系狮子沟组沉积末期形成的晚期反转构造,早期沉积的砂体在构造反转背景下可形成上倾尖灭岩性圈闭、砂岩透镜体岩性圈闭,是寻找规模岩性油藏的有利勘探目标区.

To examine the reservoir type and distribution regularity of high- and stable-yield lacustrine carbonates in the upper Member of Paleogene Xiaganchaigou Formation of Yingxi region and to determine the high-efficiency hydrocarbon exploration direction, the origin and significance of carbonate breccia in this area were investigated based on comprehensive analysis of a large number of well cores, thin sections, rock and mineral testing and log-seismic data. The study reveals that the carbonate breccia has three origins: (1) Sedimentary breccia, formed by the event-related collapse, fragmentation and re-deposition of the early weakly consolidated carbonate rock in the steep slope of underwater paleohighs due to short-term high-energy water body reformation and other geological processes. (2) Diagenetic breccia, with breccia-like structure, formed by deformation or breaking of host rock due to growth of idiomorphic and coarse crystalline gypsum-salt minerals in the weakly consolidated argillaceous carbonate rock of the penecontemporaneous period. (3) Tectonic breccia, can be further divided into fault breccia and interlayer slip breccia according to their occurrence characteristics, both of which are closely related to activity of the Shizigou thrust Fault. With a large number of partially filled pores, vugs and fractures between breccia, the two types of tectonic breccia are high- and stable-yield reservoirs in deep Yingxi region, and may occur extensively under gypsum-salt detachment layers of adjacent areas, so they are the exploration targets in the next step. Sedimentary breccia and diagenetic breccia are of great significance in searching for large-scale carbonate reservoirs.

Metamorphic rock gas reservoirs whose protolithic is sedimentary rock were found for the first time in Pingxi area, Altun foreland, Qaidam Basin. Comprehensive analysis containing core data, thin section analysis, X-ray diffraction analysis, scanning electron microscopy and confocal laser scanning shows that there are three types of shallow metamorphic rock reservoirs in Pingxi area, such as slate, “metamorphic limestone” and calc-schist which have good responses in logging and seismic data. Fractures and pores develop in epimetamorphic rock reservoir, and there are five types and eight subcategories of reservoir space. Industrial CT shows that there are differences in pores and throats of the three types of metamorphic rock reservoirs, and the fractures have a significant impact on the development of pore throats. The protolithic type is the genetic basis of epimetamorphic rock reservoirs in Pingxi area, and thin section, mineral characteristics and carbon and oxygen isotopes data show that the protolithic of epimetamorphic rock is Palaeozoic Ordovician marine sedimentary rock. Five kinds of actions, such as metamorphism, weathering, structural fragmentation, dissolution and filling, are external mechanisms of reservoir genesis. Metamorphic, weathering and structural fragmentation form fractures, and dissolution is the main cause of matrix porosity.

Based on core, thin-section, scanning electron microscopy（SEM） and well logging data, the characteristics of the parametamorphic rock reservoirs in the Pingxi area were analyzed by means of whole rock X-ray diffraction and micron CT scanning. The parametamorphic rock reservoirs mainly had three types of rocks: slate, crystalline limestone and calc-schist; the original rocks were Ordovician-Silurian marine clastic and carbonate rocks. The three types of parametamorphic rock reservoirs developed three types and six sub-types of reservoir space. The first type of reservoir space was fractures, including structural, weathered and dissolution fractures; the second type was dissolved porosities, including dissolved pores and caves; the third type was nano-sized intercrystalline porosities. The three types of parametamorphic rock reservoirs were different widely in the quantity, volume and radius of pore-throats, and were strongly affected by the type and development degree of fractures. The parametamorphic rock reservoirs were formed by metamorphism, weathering, structural fragmentation and dissolution. Metamorphism reformed the parametamorphic rock reservoirs significantly, breaking the traditional constraint of finding weathering crust at top. The parametamorphic rock reservoirs experienced five formation stages, and their distribution was controlled by rock type, metamorphic degree, ancient geomorphology, and weathering intensity.

成化湖盆过渡相组(三角洲前缘与浅湖亚相)沉积特征与淡水湖盆存在显著差异,尤其在骨架砂体微相类型、分布等方面.研究其沉积控储机制,既是对湖盆沉积学理论的重要发展,也对中国陆相盆地碎屑岩油气勘探开发具有实际指导意义.应用大量岩芯、测录井及铸体薄片资料,分析了柴达木盆地英东地区下油砂山组(Nj)与上油砂山组(N;)三角洲前缘—浅湖沉积特征及优质储层形成主控因素.研究表明,成化湖盆三角洲前缘—浅湖主要发育水下分流河道与滩坝两种储集砂体沉积微相类型.两者在沉积构造、粒度分布、微观组构及测井曲线叠加样式等方面存在显著差异.沉积微相是优质储层形成的物质基础,与湖盆水体咸化程度共同控制了优质储层的分布.成化湖盆碎屑岩储层整体成分成熟度偏低,以原生孔隙为主,溶蚀作用较弱,次生孔隙相对欠发育.强烈的早成岩期碳酸盐胶结作用增加了岩石的抗压能力.储层物性主要受控于岩石粒度与胶结物含量.

以柴达木盆地切12区冲积扇砂砾岩油藏为例,针对制约油藏开发的关键地质因素——储层非均质性,运用地质、测井及生产动态等资料,深入剖析砂砾岩储层非均质特征及其对剩余油分布的影响,认为沉积组构差异控制形成的储层孔隙结构差异是储层微观非均质性的主因,冲积扇沉积构型单元时空分布是储层宏观非均质性的主控因素.研究结果表明:厚层砂砾岩发育2类储层孔隙结构、2类渗透率韵律类型、1种夹层类型、2类夹层分布样式、2种有效砂体结构、4类有效砂体连通模式,扇中复合水道平面非均质性最强,渗透率变异系数大于0.7,扇根“泛连通体”平面非均质性中等,渗透率变异系数介于0.3～0.5.储层非均质性主要通过沉积构型单元的渗流屏障分布样式、渗透率韵律性、储层孔隙结构等方面影响剩余油的分布,导致不同构型单元剩余油分布规律不同.在扇中复合水道及水道萎缩期单元内,受注入水沿高渗层大孔道非均匀突进的影响,形成绕流、孤岛状等微观剩余油,且富集于复合韵律层的上部;在扇根“泛连通体”单元内,受注采连通性差和储层低渗透性的影响,剩余油片状富集.

柴达木英西地区下干柴沟组上段湖相碳酸盐岩储层具有岩性复杂、物性差、非均质性强的特点,是制约其勘探进程的主要原因之一.为此,依据古地貌控相、相控储层、储层控藏的地质认识,提出了以沉积旋回为单元、古地形为框架、地震—测井岩相分析为桥梁的相控分频反演方法,该方法构建的低频模型以相带为单元进行插值,有别于以距离大小进行插值的传统方法,更符合地质实际.其技术思路为:首先,通过分析明确研究区层序格架、古地貌、岩相展布规律;其次,采用分频成像、相位转换、地层切片等技术手段构建低频模型;最后采用分频非线性反演方法,利用低频模型进行约束,实现对复杂地质体的准确预测和描述.研究结果表明,英西地区目的层段优质储层发育区随着古低隆的向北迁移而不断变化,其叠合有利储层面积约为150km2,预测结果与钻井及地质规律吻合度高,为该区的进一步勘探评价提供了有效依据.

The study of sedimentary characteristics and reservoir development of shallow delta-lacustrine system is very important for the petroleum exploration and development of continental lacustrine basin.Based on a large number of drilling cores,logging and experimental analysis,the sedimentary microfacies types,sedimentary characteristics,the distribution and evolution characteristics of delta-front and shore-shallow lacustrine sediments in Youshashan Formation of Yingdong Area are summarized.The result shows that there is a big difference between the delta front and the shore-shallow lacustrine deposits in the sand ratio,stratum structure,microstructure,logging curve combination form and so on.The Pliocene successively developed the progradation sequence of shore-shallow lacustrine deposit,the transition of shore-shallow lacustrine and delta-front deposit.Under the control of deposition,reservoir maturity is not high and diagensis is of alkaline diagenetic characteristics.Microfacies and cement content are the key factors affecting reservoir physical properties.