Three-dimensional forward stratigraphic modelling of the gravel-to mud-rich fan-delta in the slope system of Zhanhua Sag,Bohai Bay Basin,China

An important hydrocarbon reservoir is hosted by the third member of the Shahejie Formation (Es₃) in the Zhanhua Sag, Bohai Bay Basin. Seismic stratal slices reveal different characteristics of channels and fan-delta lobes between the south (slope break belt) and southwest (gentle slope) areas combined with lithology, wire-line logs and three-dimensional (3-D) seismic data in the southern slope of Zhanhua Sag. And an excellent analogue has been provided for understanding various key depositional evolution of fan-deltas in the slope system (from base to top: Es₃^L, Es₃^M and Es₃^U). The Sedsim, a three-dimensional stratigraphic forward modelling programme, is applied to simulate the evolution of fan-deltas in the southern slope break systems and southwestern gentle slope systems of the Zhanhua Sag by considering a number of key processes and parameters affecting the fan-deltaic deposition from 43 Ma to 38.2 Ma. Modelling results indicate that depositional types and scales evolved from the thickest medium-scale gravel- or sand-rich fan deltas (43 Ma ∼41.4 Ma, Es₃^L) to the thinnest small-scale mud-rich fan deltas and lacustrine mud (41.4 Ma ∼39.8 Ma, Es₃^M), and lastly to less thicker larger-scale mixed sand-mud fan deltas (39.8 Ma ∼38.2 Ma, Es₃^U). The types of slope system, sediment supply and lake-level change are three controlling factors for determining the source-to-sink architecture of the gravel-to mud-rich fan-deltas and sediment-dispersal characteristics. This study has demonstrated that the process-based modelling approach can be effectively used to simulate complex geological environments and quantify controlling factors.     

Effect of pore structure on shale oil accumulation in the lower third member of the Shahejie formation,Zhanhua Sag,eastern China: Evidence from gas adsorption and nuclear magnetic resonance

As shale oil occurs primarily in micro–nano pores and fractures, research about the effect of pore structure on shale oil accumulation has great significance for shale oil exploration and development. The effect of pore structure on shale oil accumulation in the lower third member of the Shahejie formation (Es₃^l), Zhanhua Sag, eastern China was investigated using gas adsorption, soxhlet extraction, nuclear magnetic resonance (NMR) analysis, and field emission scanning electron microscope (FE-SEM) observation. The results indicated that the samples contained a larger amount of ink-bottle-shaped and slit-shaped pores after extraction than before extraction. The pore volume and specific surface area of the samples were approximately 2.5 times larger after extraction than before extraction. Residual hydrocarbon occurred primarily in the free-state form in pores with diameters of 10–1000 nm, which can provide sufficient pore volume for free hydrocarbon accumulation. Therefore, pores with diameters of 10–1000 nm were regarded as “oil-enriched pores”, which are effective pores for shale oil exploration, whereas pores with diameters smaller than 10 nm were regarded as “oil-ineffective pores”. Samples with only well-developed small pores with diameters smaller than 1000 nm showed high oil saturation, whereas samples with both small pores and also relatively large pores and micro-fractures presented low oil saturation. As the minimum pore size allowing fluid expulsion is 1000 nm, pores with diameters greater than 1000 nm were considered as “oil-percolated pores”. Large pores and micro-fractures are generally interconnected and may even form a complex fracture mesh, which greatly improves the permeability of shale reservoirs and is beneficial to fluid discharge.     

惠民凹陷古近系碎屑岩储层性质主控因素简析

惠民凹陷古近系砂岩储集层物性主要受压实、碳酸盐胶结和溶蚀作用、沉积条件控制.根据铸体薄片、阴极发光薄片、扫描电镜、物性和碳酸盐含量等数据,分析了该区储集层物性的控制因素,对各因素的影响大小和程度进行初步的定量评价.认为压实作用对孔隙度的影响主要表现在埋藏早期或碳酸盐胶结程度低的阶段,埋深每增加1000m孔隙度降低8%～9%;胶结作用对储集层性质影响与成岩演化阶段有关,成岩演化程度越高,胶结对物性的影响越大;溶蚀作用对储集层性质改善很大,产生的次生孔隙最大可达20%.溶蚀作用在宏观上受区域构造背景和生油洼陷平面位置控制,断层较发育和临近生油中心（临南洼陷）的南部斜坡带和中央隆起带溶蚀最发育.微观上溶蚀作用受岩石的粒度、分选及杂基含量控制,粒度越粗、分选越好、杂基越少的砂岩溶蚀作用越强.沉积条件对物性的影响主要表现在对原生孔隙的发育程度和对溶蚀、胶结等成岩作用的控制方面.     

孤北洼陷孔店组与沙河街组四段的多重地层划分

对孤北洼陷孔店组、沙四段生物、岩石、电性及地震地层等多重地层划分进行详细的研究,研究结果表明孔三段属灰紫色冲积产物,孔二段发育典型的暗色泥岩,沙四下亚段为红色砂、泥岩,沙四上亚段主要是灰色泥岩,夹有砂岩;电测结果表明:进入沙四下亚段时电阻率曲线相应抬起,沙四上亚段整体是一个低阻段,沙四段顶界划在下斜坡电阻的底部。孤北洼陷地层划分时要注重多重地层划分的方法,单一资料用于划分地层难于反映真实面貌。     

沾化冬枣产地土壤元素分布特征及其对冬枣品质的影响

通过对沾化冬枣产地生态地球化学环境资料的系统整理,发现土壤中有益、有害元素的分布分配、迁移转化规律和赋存特征影响沾化冬枣的品质和食用安全性。对冬枣品质影响较大的元素有Mo、Cd、Co、Hg、S、N、Se等,其中Mo、Cd、Co、Hg、S含量过高时会降低冬枣果实的品质,尤以Hg、S、Cd影响最大,而N、Se可以提高冬枣的品质。结合基础研究成果,在土壤中增加Fe、K与水提取Se有效态含量或降低有效态B、Cu、P、N含量将有利于提高冬枣品质,该研究为冬枣统筹施肥和田间管理指明了方向。     

典型陆相开放性断陷湖盆水化学场响应——以渤海湾盆地沾化凹陷为例

通过对沾化凹陷古近系1 160条数据体的试油资料,内容包含矿化度、水型、各离子含量(氯离子、钠离子、钙离子、镁离子、碳酸氢根离子、硫酸根离子等)、原油物性(原油密度、粘度、凝固点及含蜡量等)的分析,对沾化凹陷古近系的水化学场特征进行了研究,研究结果表明,与东营凹陷古近系沙河街组三段与四段封闭性滞留型水化学场特征明显不同,沾化凹陷古近系在宏观上呈现一系列开放性敞流湖盆水化学场的重要特征:矿化度及各离子含量较低(矿化度平均在10 g/L 左右),平面上水化学场环带状特征及剖面上的分带性不明显,而主要呈现平面的分区性及剖面的旋回性; 主要发育NaHCO₃型地层水(比例达到80%),变质系数、碳酸盐平衡系数高(分别在1.0和50以上),显示地层水变质作用及交替活动能力强; 不同类型地层水Cl^--HCO₃^-响应有明显差异,低矿化度NaHCO₃型地层水rCl^-/r(HCO₃^-)比值基本小于10,表明研究区溶解、溶蚀作用明显; 少量Ca²⁺ 和Mg²⁺ 负相关性显示,在研究区这种白云岩化作用主要发生在CaCl₂型地层水中; Na⁺-Ca²⁺ 关系显示,Na相对亏损、Ca相对富集特征不明显,代表Ca的相对富集数量的流体线(Ca_excess=0.997 4(Na_deficit)＋29.355(R²=0.859 6))远低于世界平均盆地流体线; 原油物性响应明显,研究区大多次生稠油分布在低矿化度型地层水中,显示了原油在开放性敞流型湖盆地层水载体中发生运移、聚集时的稠化作用。受湖盆中各次级洼陷的不均衡性发育和演化,研究区这种总体开放性敞流湖盆水化学场特征并不排除局部(如渤南洼陷)有封闭性滞留型湖盆水化学场特征。     

二连盆地白音查干凹陷层序地层及其油气勘探意义

基于测井和地震资料分析, 识别了二连盆地白音查干凹陷的层序界面, 建立了凹陷层序地层格架, 研究凹陷内部沉积相类型及其平面展布特征, 并建立了单断箕状断陷盆地沉积相模式。根据油气生、储、盖组合特征, 预测腾格尔组(层序Ⅲ)和都红木组一段(层序Ⅳ)为油气有利成藏层位, 南部缓坡河道砂体储集层和北部陡坡冲积扇储集层为油气有利储集相带, 达尔其断块和桑合地区为油气有利成藏区块。      

江汉盆地潜江凹陷岩性油藏形成条件及分布规律研究

潜江凹陷单向多物源的盐湖沉积体系及构造背景决定了其具有形成多种成因类型岩性油藏的地质条件,按圈闭成因将潜江凹陷岩性油藏分为4亚类15小类.砂岩尖灭线与构造的有机配合是形成岩性油藏的主要因素.纵向上,岩性油藏主要发育于潜三-潜四段,平面上主要发育于面迎物源的构造上倾斜坡和断层与砂岩侧缘尖灭配置集中分布区.      

鲁北济阳坳陷沾化凹陷东部潜山的发育及油气成藏控制因素

通过对沾化凹陷东部主要断裂发育演化的特征和主要地震测线的平衡剖面、伸展率分析,对该地区潜山发育过程及其与盆地演化的关系进行了研究,并就潜山油气成藏的控制因素进行了分析。结果表明,沾化凹陷东部潜山发育可以划分为早—中三叠世、晚三叠世、早—中侏罗世的潜山发育前期,晚侏罗世—白垩纪的潜山发育期,古近纪的潜山改造、定型期和新近纪—第四纪的潜山成藏期,断裂活动是本区潜山形成演化的主控因素。沾化凹陷东部潜山油气成藏主要受控于该区中、新生代盆地的叠合关系,中生代凸起和古近纪凹陷的叠合部位是最有利的潜山油气成藏区,中生代凸起和古近纪凸起的叠合部位不利于潜山成藏,往往形成潜山披覆背斜油气藏。     

冀中坳陷束鹿凹陷横向调节带成因分析

束鹿凹陷是冀中坳陷西南部的一个典型的伸展单断凹陷,构造格局简单,存在北东向伸展断裂系统和北西向横向调节带.通过凹陷演化史以及钻井资料分析,探讨横向调节带形成机制和形成时期,提出Ⅰ级调节带形成于凹陷强烈伸展期,Ⅱ级调节带形成于凹陷弱伸展时期.研究认为,边界断裂不均匀伸展和基底古隆起控制Ⅰ级横向调节带的形成,岩性组合差异是Ⅱ级横向调节带形成的引发机制,控洼断层的侧列状交替发育是构造Ⅱ级横向调节带形成的动力机制.