Mineral composition and organic geochemistry of the Lower Cretaceous Xiagou Formation source rock from the Qingxi Sag,Jiuquan Basin, Northwest China

The Lower Cretaceous Xiagou Formation contains the major source rocks for the crude oils discovered in the Qingxi Sag and the South Uplift in the Jiuquan Basin, northwestern China. The Xiagou Formation source rock was formed in a closed,anoxic, reducing, alkaline lacustrine environment with a high salinity. Its high content of brittle minerals is favorable for the fracturing of reservoirs in source rock formations in the Qingxi Sag. The Xiagou Formation contains a great number of fair to excellent source rocks, and their organic matter（OM） came chiefly from plankton/algae and high plants as well as possibly bacterial organisms. The Xiagou Formation source rocks mainly contain Type II OM and some Type III and Type I OM, with good oil-generating potential. The source rock maturity is mainly in the early-mature and mature stages, and its Rovalue corresponding to oil peak is about 0.8%, which is lower than classic oil peak Rovalue of 1.0%; therefore, a great deal of hydrocarbon was generated before the classic oil peak Ro= 1.0%. Mature source rock in the Xiagou Formation tends to be distributed in the older members and at a greater depth. There is a better exploration potential of tight oil in the deep Qingxi Sag.

Orbital cyclicity in sedimentary sequence and climatic indications of C-O isotopes from Lower Cretaceous in Qingxi Sag, Jiuquan Basin, NW China

Sedimentary deposits of the Lower Cretaceous Xiagou Formation form the most significant potential hydrocarbon reservoirs in the Qingxi Sag, Jiuquan Basin(NW China). Zircon U-Pb ages of the dated basalts at the top of the Xiagou Formation give an isochron age of 115.6 Ma, and the sedimentation interval of the Xiagou Formation was speculated to range from about 125/124 Ma to 115 Ma based on paleontological research and stratigraphic correlation analysis. Here we use GR logging data as a palaeoenvironmental and palaeoclimatic proxy to conduct a detailed cyclostratigraphic study of five selected wells. Power spectra, evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in the Xiagou Formation. The ratios of cycle wavelengths in these stratigraphic units are 33.82 m : 7.91 m : 3.06 m : 1.79 m, which is similar to the ratio of orbital targets of 20 : 5 : 2 : 1. The ratio of 20 : 5 : 2 : 1 is interpreted as Milankovitch cycles of 405 kyr long eccentricity,100 kyr short eccentricity, 37 kyr obliquity, and 22 kyr precession cycles respectively. A high-resolution astronomical time scale is constructed by tuning the stratigraphy into target curves of orbital cycles respectively. Based on the astronomical time scale, the absolute ages of 55 samples were estimated,which are used for subsequent stable carbon and oxygen isotope stratigraphy analysis. The analysis results of the five studied wells in the Qingxi Sag indicate:(1) a negative trend of δ^(13)C values upwards in the Xiagou Formation, and(2) negative δ^(18)O values with a positive trend upwards. Both relatively heavy values and pronounced covariances of δ^(13)C values and δ^(18)O values indicate an arid-evaporationcontrolled climate during the sedimentary period of the Lower Cretaceous Xiagou Formation, Qingxi Sag, Jiuquan Basin. Moreover, positive covariances of SQK_1g_(2+3) indicate extremely high temperature, and negative covariances of SQK_1g_1 indicate a relatively low temperature.

Organic matter enrichment in the first member of the Xiagou formation of the lower Cretaceous in the Jiuquan Basin, China

The sources and enrichment of organic matter in a sediment core in the first member of the Xiagou Formation(K_1g^1) from the Chang 2-2 borehole of the Jiuquan Basin,NW China,have been examined using Rock-Eval,maceral,carbon isotopes and biomarker data.This data indicates that highly variable organic matter sources and preservation conditions in response to climate change.TOC content,HI,and δ^(13)C value were strongly correlated with the abundance of gammacerane,woody organic matter content,steranes/hopanes ratio,and C_(29) sterane content.This correlation demonstrates the importance that the control of the salinity of the depositional environment and organic matter sources can have upon the enrichment,type,and carbon isotopic composition of organic matter.In the Jiuquan Basin's relatively high temperature and arid climate,high salinity lakes with high primary productivity of algae,planktons,and bacteria,and good organic matter preservation conditions(anoxic bottom water) resulted in the enrichment of isotopically-light algae-bacterial organic matter.In the Jiuquan Basin's regions with a relatively low temperature and wet climate,fresh lakes with low primary productivity of algae,planktons,and bacteria received significant terrigenous high plants input,resulting in the deposition of a low abundance of isotopically heavier terrestrial organic matter.

Types, distribution and play targets of Lower Cretaceous tight oil in Jiuquan Basin, NW China

Based on drilling and laboratory data, the formation conditions of tight oil reservoirs in the Jiuquan basin were comprehensively analyzed and the exploration domains were sorted out. The Jiuquan basin underwent three cycles of lake level fluctuation in early Cretaceous, leaving three sets of high-quality source rocks, the Zhonggou, Xiagou and Chijinbao Formations in the Lower Cretaceous. There are two types of reservoir assemblages, source-reservoir in one type and source below reservoir type, and two types of tight reservoirs, argillaceous dolomite and conglomerate. The "sweet spots" control the enrichment of oil and gas. Argillaceous dolomite tight oil reservoirs have the characteristic of "integrated source-reservoir", with fractures connecting the matrix micro-pores, pore-fracture type and fracture-pore type "sweet spots" distributed in large scale. The sandy conglomerate tight oil reservoirs were formed by source-reservoir lateral connection, and can be divided into source below reservoir type, source-reservoir side by side type and "sandwich" type. The overlapping areas of the favorable facies belts of fan-delta front and the secondary pore developing belts are the "sweet spot" sites. The favorable areas for seeking conglomerate tight oil are fan-delta front deposits around the Qingxi, Ying'er and Huahai sags, with an exploration area of 550 km^2; while the area to seek argillaceous dolomite tight oil is the NW fracture developed belt in Qingxi sag, with an exploration area of 100 km^2.

Paleomagnetic dating of the Jiuquan Gravel in the Hexi Corridor:Implication on mid-Pleistocene uplift of the Qinghai-Tibetan Plateau

The sediments in the foreland basins around the Qinghai-Tibetan Plateau preserved crucial information to reveal its tectonic history. In the Hexi Corridor, north periphery of the Qinghai-Tibetan Plateau, the angular unconformity between the Jiuquan Gravel and the Yumen Conglomerate has been well known to represent an intensive tectonic event of the plateau. However, its age is poorly constrained. Our paleomagnetic dating at the Laojunmiao section in the Jiuxi Basin show that the bottom of the Jiuquan Gravel reaches 0.84 MaBP, the top of the Yumen Conglomerate is about 0.93 MaBP. This result clearly demonstrates that the northern Qinghai-Tibetan Plateau experienced an intensive movement at mid-Pleistocene.

Primary dolostone related to the Cretaceous lacustrine hydrothermal sedimentation in Qingxi sag, Jiuquan Basin on the northern Tibetan Plateau

Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1-1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values （C^ISOpDB） range from 5.89%~ to 14.15%o with an average of 9.69%0. The ratio of 87Sr/86Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca2＋, Mg2＋ and Fe2＋. Under the driving flow power of magmatic heat, gravity and compaction, the hy- drothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered ＂hydroexplosion breccias＂. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hy- drotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.

Lacustrine Basin Fills in an Early Cretaceous Half-Graben, Jiuquan Basin, NW China: Controlling Factors and Implications for Source Rock Depositional Processes and Heterogeneity

Studies on basin fills have provided significant insights into reservoir distribution and prediction in petroliferous basins, however, the effect of basin fills on source rock properties has been underexplored. This paper documents basin filling characteristics and their implications for depositional processes and heterogeneity of source rock in the Qingnan subsag of the Jiuquan Basin, by using subsurface geological data from recent hydrocarbon exploration efforts in this area. Drill core data reveals that the basin fill of the Qingnan subsag was dominated by fan delta-lacustrine systems, in which deposition of the fan deltas along the basin margin was mainly through gravity flows. The temporal and spatial evolution of the depositional systems indicates that the basin fill was characterized by a continuously retrogradational process, with decreasing extent of fan deltas in vertical succession. Weakening of tectonic activities and climate change from humid to semi-arid are interpreted to be the main control factors that were responsible for the retrogradational basin fill. The different depositional environments in the early stage and late stage of the retrogradational basin filling history resulted in the different depositional processes and properties of source rocks. This study suggests that source rock heterogeneity associated with basin fills in lacustrine basins should be considered in hydrocarbon exploration.

提升酒泉化工园区产业链现代化水平对策研究

伴随中国化工产业的供给侧结构性改革,化工园区化发展的层次和水平从1.0阶程进入2.0阶程。酒泉市作为“丝绸之路经济带”重要节点城市及甘肃省扩大向西开放的通道和枢纽,应充分发挥政策、区位、环境、产业集聚等优势,逐步提升化工园区产业链现代化水平,创造更好条件积极承接我国中东部地区优质化工企业转移。结合实际调研情况,分析酒泉市化工园区的特点,阐述酒泉市提升化工园区产业链现代化水平的具体对策措施,旨在为酒泉市化工产业的现代化发展提供参考和理论依据。

酒泉市猪圆环病毒2型和3型的流行病学监测和分析

为掌握酒泉市五个农业县猪圆环病毒2型(PCV2)和3型(PCV3)流行情况,在辖区内不同区域、不同养殖规模、不同生长阶段的19个规模化养殖场、38个散养户、4家屠宰场采集血清样品230份、粪便样品250份、猪肺脏、扁桃体、颌下淋巴结等组织样品220份,进行PCV2和PCV3核酸检测,检出阳性样品138份,阳性率为21.23%,PCV2的阳性率为15.54%,PCV3的阳性率为5.69%,表明PCV2的流行比PCV3更普遍、阳性感染率更高,但在不同区域、不同规模猪场的危害程度和流行情况存在一定的差异。规模养殖场的总体阳性感染率明显低于散养户,保育猪的感染率高于其他生长阶段的生猪。本次实验对酒泉市猪场PCV感染综合防控提供技术支撑,为科学养猪产生积极影响。

2013—2022年酒泉市声环境质量变化趋势分析

根据2013—2022年酒泉市声环境监测数据,综合评价酒泉市的声环境质量变化趋势。结果表明,酒泉市的声环境质量整体呈持续向好态势,城市区域和功能区声环境轻微改善,声源构成中,交通噪声和生活噪声占比最大。针对分析结果,提出酒泉市声环境防控措施,进一步推动全市声环境质量持续改善。

酒泉市农产品物流发展研究——基于SWOT分析

党的二十大报告中强调要加快发展物联网。建设高效顺畅的农产品物流体系,有助于实现农业经济发展。酒泉市发展农产品物流的过程中,面临着物流专业人才短缺、政策法规不健全、缺乏监管机制以及物流成本过高等诸多问题。通过SWOT分析法对酒泉市农产品物流发展的优势和劣势,面临的机遇和威胁进行分析,提出通过加强政府宏观调控、完善物流行业法律法规;培养农产品物流人才,促进物流先进技术应用;加强基础设施建设,加快农产品物流信息化,提升供应链的可追溯性。推动酒泉市农产品物流发展。

基于GIS系统的酒泉市降水量时空变化特征及演变趋势研究

酒泉市地处河西走廊西段,气候极其干旱,为了能够有效掌握区域内降水量的变化特征及演变趋势,收集酒泉市境内代表站点的降水量长系列资料,基于GIS系统构建了泰森多边形,计算酒泉市区域内多年平均降水量。采用数学统计法、线性回归法、Mann-Kendall法,对区域降水量从年内分配、年际变化、空间变化、演变趋势、突变年份等方面进行深入计算与研究。结果表明,酒泉市降水量年内分配主要集中在5—9月,以6—8月最为集中,7月达到极值,年内分配极不均匀;年际降水量变差系数Cv值为0.28,年际变化相对稳定;降水量随高程增加而增加,由西南向西北逐渐递减;年降水量增长值为77.3mm,增长率为1.3mm/a,突变年份出现在1964年、1967年、1981年、1986年。研究结果可为今后酒泉市区域内水资源合理配置提供数据支撑,也可为气候变化研究提供参考依据。

2013—2022年酒泉市肃州区大气降水变化特征及其源解析

通过系统地分析2013—2022年酒泉市肃州区连续10年的大气降水季节变化及相关性,并运用正定矩阵因子分解法(PMF)解析其主要来源,旨在掌握酒泉市肃州区大气降水特征,为地方经济健康发展和大气污染防治政策的制定提供科学依据。

酒泉金塔胡杨林绿色空间景观规划设计

本文首先阐述西北地区胡杨林概况,然后分析了酒泉金塔胡杨林发展现状,以及酒泉金塔胡杨林绿色空间景观规划设计注意事项,最后围绕规划定位、规划分区、植被的恢复与配置,对胡杨林绿色空间景观规划设计措施进行探讨。

盛唐酒泉西沟“骑士模印砖”图像研究——以1、2、3号墓为例

对盛唐酒泉西沟“骑士模印砖”从图像学与绘画艺术风格两方面展开论述分析,图像直观反映了画面主题寓意与象征含义,并采用线条、设色、空间性等艺术风格将骑士和战马表现得生动形象。以盛唐酒泉西沟1、2、3号墓中骑士模印砖为例展开分析,与同一时期《马球图》壁画、《骑士巡行》模印砖进行比较,从图像学图像志视角对酒泉西沟“骑士模印砖”进行解读,描绘了唐代河西地区骑士出行的真实景象。

酒泉市猪繁殖与呼吸综合征的流行病学监测和分析

为掌握酒泉市猪繁殖与呼吸综合征(PRRS)的流行情况,本试验在酒泉市五个农业县市采集638份样品,采用反转录-聚合酶链式反应(荧光RT-PCR)方法进行核酸检测,对不同地域、不同生长期、不同饲养模式的流行情况进行分析。结果显示,638份样品共检测出PRRS核酸阳性样品29份,PRRS阳性感染率为4.55%。不同地域PRRS阳性感染率介于0-7.95%;屠宰场、规模场、散养户PRRS阳性感染率分别为0、2.96、6.82%;种公猪、育肥猪、仔猪、母猪PRRS阳性感染率分别为0、3.1、5.38、6.36%。结果表明,酒泉市PRRS呈散发流行,规模养殖场标准化高,饲养管理模式先进PRRS阳性感染率低,此病仔猪和母猪更容易感染,本试验将对我市PRRS综合防控提供技术支撑。

致密油源储组合差异富集机制与控藏模式——以酒泉盆地青西凹陷为例

源储品质及其空间匹配组合类型是致密油充注成藏与富集的关键因素,然而目前对其认识不足,尤其对不同类型源储组合致密油充注成藏与富集的差异性及其形成机制缺少深入研究,制约了致密油成藏理论的形成与勘探开发进展。以酒泉盆地青西凹陷为例,通过野外观察、岩心描述、钻井分析,总结出下源上储、上源下储、三明治型3种基本类型,源储一体、源储(薄)互层2种特殊类型,下源上储Ⅱ型、上源下储Ⅱ型、三明治Ⅱ型3种复合类型共8种类型的致密油源储组合,其中前5种为常见的源储组合类型。钻探成果统计与核磁共振实验相互验证了源储组合类型与致密油富集的对应关系,即源储一体型致密油富集程度最高,其次是三明治型,上源下储型要好于下源上储型,薄互层型不利于致密油的成藏与富集。揭示了下源上储、上源下储、三明治、源储一体、薄互层5种常见源储组合类型的致密油充注成藏与富集机制及其差异,总结了这5种源储组合致密油充注成藏与富集模式,指出致密油成藏动力、充注方式、保存条件是控制致密油充注成藏机制与富集差异的主控因素,而这些主控因素又与致密油源储组合类型密切相关。

基于层次分析法和变异系数法的酒泉市水资源承载能力分析评价研究

水资源承载能力分析是研究区域社会经济可持续发展的重要内容之一,近年来广受人们关注。以酒泉市为研究对象,选取10项指标构筑酒泉市水资源承载能力指标体系,通过层次分析法和变异系数法量化评价酒泉市2010-2021年水资源承载能力。结果表明:层次分析法评价2010-2021年酒泉市水资源承载能力为Ⅱ级,水资源轻度超载;变异系数法评价表明2010-2017年,酒泉市水资源承载能力在Ⅱ级~Ⅲ级之间波动,2018年后,酒泉市的水资源承载力等级转变为Ⅲ级,水资源濒临超载。综合分析认为变异系数法的分析结果更符合酒泉市实际情况。

酒额铁路不同沙障防沙性能对比

风积沙害是风沙地区铁路安全运营的重要隐患,合理选择高效的沙障是减轻铁路沙害的关键。基于现场测试和数值模拟结果,对比分析了酒额铁路沿线竹排式沙障和HDPE板沙障的防沙性能。研究结果表明:数值模拟与现场测试结果基本一致,验证了数值模型的可靠性;两种沙障有效防护区面积和背风侧大循环泡的面积与来流风速呈负相关,说明随着风速的增加沙障的防沙效率呈递减趋势;与HDPE板沙障相比,竹排式沙障的风速衰减能力更强,有效防护区面积和循环泡面积更大,表明后者的防沙性能更优;两种沙障对粗颗粒的拦截效率明显高于细颗粒,但竹排式沙障拦截细颗粒的效率更高。

2021年酒泉阿克塞县M_(s)5.5地震前地电场变化分析

2021年8月26日酒泉阿克塞县发生M_(S)5.5地震,基于距震中500km范围内6个地电场观测站2020-2021年的观测资料,利用大地电场岩体裂隙水(电荷)渗流(移动)模型,计算了地电场观测站优势方位角,结合震源机制以及安西站定点形变观测资料,分析获知:①震前山丹、高台、白水河3个观测站的优势方位角出现异常变化,异常开始时间集中在2021年5月,表现出一定的同步性;瓜州、都兰、嘉峪关3个观测站优势方位角无明显异常变化。②安西站伸缩仪、垂直摆与相距约12km的瓜州站地电场,其日均值数据在2021年4-7月出现近乎同步的趋势转变、加速、跃变等异常变化现象,显示出不同物理参数间具有关联性。应用地电场与定点形变观测数据,通过综合分析、相互印证,判断区域应力状态变化,为探索不同物理参数异常演化在数据可靠性分析、地震预测中的应用等提供了思路。