Distribution of the Ordovician Fluid in the Tahe Oilfield and Dynamic Response of Cave System S48 to Exploitation

The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a crossformational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI^- and K^＋＋Na^＋, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified： （1） residual water at the bottom of the cave after oil and gas displacement, （2） residual water in fractures/pores around the cave after oil and gas displacement, and （3） interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br^- concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enri     

辽宁省典型地区高氟地下水的分布特征及成因分析

在前人研究的基础上,通过水文地质调查、综合物探法、水化学及水质检测方法,探测辽宁省典型地区水化学特征,分析了水化学特征与地下水氟离子的含量关系;不同地貌单元地下水氟离子含量分布不同;主要从高氟地下水形成的物质基础,水文地质环境对氟离子变化的制约,粘性土层是富集氟离子最好场所等方面分析辽宁高氟地下水的形成原因,通过研究了解到高氟地下水一般存在于潜水的上部及粘土层中,这一研究为今后寻找低氟水源提供前期有力资料奠定基础。     

煤层气群井排采地层水来源判识及其意义

为指导煤层气生产区煤层气井排采,以沁水盆地南部樊庄区块生产监测区为例,通过系统采样测试分析了不同时间节点煤层气井产出地层水样的离子浓度变化特征、溶解性总固体、电导率和总硬度的变化特征,判识了产出地层水的水质类型和水化学相。研究表明:产出地层水的离子浓度、溶解性总固体、电导率和总硬度呈现出波动性变化的特征,具有明显的一致性,地层水中离子浓度除受地层水来源、矿物和离子性质影响外,还受区域井间干扰形成条件下煤层气井产出地层水的流体场影响。产出地层水质类型主要为HCO3—Na型,部分为Cl—Na型,产出地层水水化学相主要为煤层水,部分煤层气井产出地层水水化学相为顶底板围岩水(砂岩或泥岩水)或混有顶底板围岩水的煤层水。生产监测区煤层气群井排采地层水来源的判识有利于指导煤层气生产区排采控制。     

塔里木盆地西部古盐矿点卤水水化学特征与找钾研究

在塔里木盆地发展地史上,白垩纪—第三纪时曾有过多次大的海浸,带来了丰富的盐类物质成分,又由于干旱封闭的气候环境,其西部沉积了广阔而厚层的盐岩,因此一直被列为我国有利的找钾远景区。在对塔里木盆地西部晚白垩—第三纪地层出露盐矿点实地考察的过程中,采集、分析了一些卤水样品的水化学组成,通过K+含量及一些水化学系数变化特征的研究,查明了卤水的成因类型属石盐岩淋滤水,K+含量较低,没有出现显著水化学系数异常;但相比之下,塔里木盆地西南喀什坳陷构造区Br含量值明显高于库车坳陷,Br×103/Cl值等具找钾意义的水化学系数比其他地区高1～2个数量级,推测淋滤的盐层当时的成盐古卤水浓缩程度较高,Br出现相对的富积,有一定的找钾远景;另外,对比海水蒸发实验结果,发现卤水的化学成分明显不同于经典的海相成盐淋滤卤水,指示海相标志的Br、B等含量较低,反映了该区成盐环境是在海陆相互作用的复杂条件下形成的,今后的找钾工作不能局限于经典的海相成盐理论,应该结合岩盐及含盐系地层地球化学、盆地构造变形历史及构造分异特征的综合分析研究,寻找新的找钾指标,以期在喀什坳陷等更深一级次级盆地发现可能的钾盐矿床。     

Seasonal Variations of Hydrochemical Characteristics of Groundwater in Changping Plain,Beijing

Changping Plain, located in the northwest of Beijing, has become an important groundwater recharge area for the Beijing Plain and an important source for the urban water supply. In this study, groundwater samples were collected during the dry and wet seasons in 2015 from 24 monitoring wells distributed in Changping Plain. A Piper-Tri-linear diagram, a Schoeller diagram, a Gibbs diagram, and the isotope technique were used to investigate the temporal and spatial variations in the concentrations of groundwater hydrochemicals and the sources of groundwater recharge. The results indicated: 1) seasonal variations in the concentrations of HCO₃^-, Ca²⁺, and Na⁺ were significant; the spatial variations of these ions were more dramatic in the dry season than in the wet season due to the dilution effect of precipitation; 2) Most groundwater samples had a HCO₃-Ca-Mg based hydrochemical type and a few had a HCO₃-Na-K based hydrochemical type; the hydrochemical type tended to evolve from HCO₃-Ca-Mg based to HCO₃-Na-K based in some monitoring wells that showed distinct seasonal variation; 3) the groundwater in the study area originated mainly from atmospheric precipitation, and it is affected by evaporation and concentration processes.     

淮南煤田地下水水化学空间分布及其形成作用

为探究淮南煤田地下水的空间分布情况及各项水化学作用的强度,将淮南煤田划分为松散层较厚的北部区域与松散层较薄的南部区域,收集了两区域16个矿井主要突水含水层的水化学测试数据,综合采用离子组合法、Gibbs图、氯碱指数等方法研究了各含水层的地下水水化学特征。研究结果表明：地下水总溶解固体与松散层埋藏厚度呈正相关,其均值范围在951.92~2 667.79 mg/L。随着松散层厚度的增大,脱硫酸、浓缩结晶及阳离子交替吸附等水化学成分形成作用得到增强,使SO₄^2-不断消耗形成HCO₃^-,导致溶解度小的HCO₃^-结合Ca²⁺、Mg²⁺析出,并最终形成以NaCl主导的高矿化度水体。该结论将为深部煤矿区水害防治、水资源利用等提供一定借鉴作用。     

山东莱芜盆地西北缘古近系半固结含水岩组的特征及其成因

通过岩心、测井、地下水常规离子组分及氢氧同位素样品测试对分布在莱芜盆地西北缘古近系半固结含水岩组物性、水化学特征及地下水补给循环特征进行研究;结合古新世以来盆地沉积演化史及含水层成岩阶段划分,分析半固结含水层地下水富集模式.结果表明,埋深100 m以下的古近系砂砾岩含水层,长期处在早成岩A期,呈弱固结-半固结状态,兼具裂隙与孔隙含水层特性,且以孔隙为主.与碳酸盐岩含水层水化学特征相似,水化学类型为HCO3-Ca?Mg型,现代大气降水作为地下水主要补给来源,蒸发浓缩作用,碳酸盐岩、石膏及盐岩溶解参与了地下水化学组分形成.在莱芜盆地北部边界断裂处,部分断裂所夹断块可作为古近系含水岩组应急找水靶区.     

小秦岭义寺山金矿床地质特征及找矿标志①

义寺山金矿床位于小秦岭金矿田东端,区内燕山期岩浆活动强烈,成矿条件优越。赋矿围岩为太古界太华群的中深变质岩系。金矿体与韧-脆性构造带关系密切。矿体以含金硫化物石英脉为主,膨大收缩、分枝复合、尖灭再现现象普遍。主要围岩蚀变为硅化、钾化、绿泥石化和绿帘石化。金与多金属硫化物(尤其是黄铜矿和黄铁矿)及石英脉关系密切。岩石地球化学测量结果表明矿(化)体与原生晕异常叠合较好,对找矿有重要意义。硫化物石英脉、蚀变韧-脆性剪切带和围岩蚀变是主要的找矿标志。     

利用水化学特征识别桑树坪煤矿突水水源

及时准确地找到突水水源,是解决矿井突水问题的关键。通过对桑树坪煤矿主要含水层水样进行常规水质分析,并通过Piper三线图揭示了矿区不同地下水含水层的水化学特征,并通过出水点与背景值的水文地球化学特征对比,正确地判断出了该矿区突水水源为奥灰岩溶水。研究认为,水化学特征分析是一种快速判别突水水源的有效方法。     

小波分析在前郭水化观测资料处理中的应用

本文从小波变换原理入手,选取正交小波（Daubechies小波）对前郭井近10年水化观测资料进行分析,结果表明小波分析可以很好的抑制数据的干扰,将原始信息中高频信息和低频信息分辨出来。运用小波变换对观测资料进行处理后,映震效果明显优于原始资料,一些趋势变化和短临变化更直观,异常信息更加丰富,更有利于利用前兆数据进行地震预测。