川西坳陷中段地層水地球化學(xué)特征及油氣保存條件
發(fā)布時(shí)間：2018-09-11 20:49
【摘要】：地層水為含油氣盆地中流體的重要組成部分,地層水的形成及其活動(dòng)規(guī)律與油氣的生成、運(yùn)聚以及油氣藏的形成、保存和破壞有著非常密切的關(guān)系。川西坳陷是晚三疊世以來由前陸盆地逐漸發(fā)展演化而來的坳陷盆地,沉積了巨厚的晚三疊世-白堊紀(jì)地層,已經(jīng)發(fā)現(xiàn)了多套含氣層系,在這些含氣層中普遍存在高礦化度地層水。在地質(zhì)歷史時(shí)期,地層水與圍巖和油氣之間普遍存在物質(zhì)與能量的交換,而地層水的地化特征正是這些反應(yīng)過程的直接記錄者,蘊(yùn)含了許多與油氣藏形成和保存相關(guān)的信息。本文以須二段、須四段、中侏羅統(tǒng)以及上侏羅統(tǒng)地層水資料為研究基礎(chǔ),詳細(xì)分析了研究區(qū)地層水基本地球化學(xué)特征,結(jié)合工區(qū)地質(zhì)背景,全面分析了研究區(qū)地層水類型的成因及地層水初始來源,并且討論了研究區(qū)水文地質(zhì)保存條件。首先區(qū)分出了研究區(qū)氣井產(chǎn)出水的性質(zhì),通過凝析水與液態(tài)地層水的礦化度、日產(chǎn)水量以及水氣比的差異,將TDS10000mg/l的水樣品定義為凝析水,將TDS≥10000mg/l的水樣品定義為地層水,在此基礎(chǔ)上,通過對比分析研究區(qū)各層系地層水礦化度特征,反映出上三疊統(tǒng)地層水礦化度明顯大于侏羅系,上三疊統(tǒng)地層水以鹵水為主,侏羅系地層以鹽水為主;上三疊統(tǒng)地層中,須二段地層水礦化度大于須四段,侏羅系地層中,中侏羅統(tǒng)地層水礦化度大于上侏羅統(tǒng),總體上研究區(qū)地層水礦化度具有隨埋深增加而增加的正常演化特征。通過對研究區(qū)地層水類型的分析,工區(qū)主要以Ca Cl2型地層水為主,以及少量的Mg Cl2型和Na HCO3型,但在上侏羅統(tǒng)出現(xiàn)較多Na2SO4型,從上侏羅統(tǒng)到須二段,水型由Na2SO4型逐漸過渡到Ca Cl2型,礦化度逐漸增高。地層水中主要陽離子是Na+,主要陰離子為Cl-。不同產(chǎn)層地層水陽離子含量大小關(guān)系均表現(xiàn)為Na+Ca2+K+Mg2+,須二段、須四段和中侏羅統(tǒng)地層水中陰離子含量大小關(guān)系均表現(xiàn)為Cl-HCO3-SO42-,而上侏羅統(tǒng)地層水中陰離子則表現(xiàn)為Cl-SO42-HCO3-。通過與海洋、湖泊以及河流中微量元素含量的對比,研究區(qū)地層水還表現(xiàn)為明顯富集微量元素Li、Sr、Ba、Br和Fe,表明研究區(qū)地層水經(jīng)歷了一定程度分蒸發(fā)作用以及水巖相互作用;并且須家河組地層特別富集Br,其富集原因可能主要來自成巖過程中有機(jī)質(zhì)釋放出來的Br。基于詳細(xì)的地層水地球化學(xué)特征,結(jié)合區(qū)域地質(zhì)特征,分析了研究區(qū)不同類型地層水的成因,結(jié)果表明,須二段與須四段少量的高礦化度Na HCO3型水的形成最有可能與烴源巖有機(jī)成因的CO2有關(guān);中侏羅統(tǒng)與上侏羅統(tǒng)Na HCO3、Na2SO4型最可能是原生的陸相成因地層水,須二段Na2SO4型水可能是Ca Cl2型水與Na HCO3型水這兩類地層水混合而成;須四段Mg Cl2型水更可能是原始海相地層水,而上侏羅統(tǒng)Mg Cl2型水則主要是由下伏須家河組高礦化度Ca Cl2型水與上侏羅統(tǒng)低礦化度Na HCO3型水經(jīng)混合作用而成;中侏羅統(tǒng)與上侏羅統(tǒng)Ca Cl2型水主要是由下伏須家河組高礦化度地層水經(jīng)過斷層運(yùn)移而來。通過分析地層水的化學(xué)組成特征,現(xiàn)今地層水Na-Cl特征與海水蒸發(fā)曲線、淡水蒸發(fā)曲線的關(guān)系表明研究區(qū)須二段、須四段地層水均起源于海水,并且海水蒸發(fā)程度較弱,主要表現(xiàn)為低蒸發(fā)程度海水的特征;侏羅系地層水主要為陸相大氣淡水與上三疊統(tǒng)外來海水的混合水體特征。地層水氫氧同位素特征的分析表明研究區(qū)地層水以海水與大氣水混合成因水為主,上三疊統(tǒng)地層水為混合水體,相對侏羅系地層水表現(xiàn)為更富海水的特征,少量上三疊統(tǒng)地層水因受地層水與CO2同位素交換的影響而表現(xiàn)出明顯的δ18O負(fù)漂,呈現(xiàn)出大氣水成因特征,但是實(shí)際上仍是混合水;侏羅系地層水以混合水體為主,中侏羅統(tǒng)地層水較上侏羅統(tǒng)地層水更富海水組分,少數(shù)侏羅系地層水仍保持著大氣水的特征。研究區(qū)發(fā)育優(yōu)質(zhì)的蓋層條件,主要斷層大多數(shù)封閉性能都較好,通過地層水化學(xué)特征參數(shù),如鈉氯系數(shù)、脫硫系數(shù)?碳酸鹽平衡系數(shù)?氯鎂系數(shù)等的組合特征的分析,顯示出研究區(qū)大部分地層水具有濃縮程度高、變質(zhì)程度深的特征,侏羅系地層的封閉性較上侏羅統(tǒng)差,特別是上侏羅統(tǒng)出現(xiàn)了較多Na2SO4型地層水,油氣保存最條件相對較差;須二段與須四段地層相對更為封閉,更有利于油氣保存。
[Abstract]:Formation and activity of formation water are closely related to the generation, migration and accumulation of oil and gas, formation, preservation and destruction of oil and gas reservoirs. Western Sichuan depression is a depression basin evolved from foreland basin since Late Triassic and deposited huge thickness of Late Triassic. In the Permian-Cretaceous strata, many sets of gas-bearing strata have been discovered, in which high-salinity formation water is ubiquitous. In geological history, the exchange of substance and energy between formation water and surrounding rocks and oil and gas is widespread, and the geochemical characteristics of formation water are the direct recorders of these reaction processes, containing a lot of oil and gas. Based on the formation water data of Xu 2, Xu 4, Middle Jurassic and Upper Jurassic, the basic geochemical characteristics of formation water in the study area are analyzed in detail. Combined with the geological background of the work area, the genesis of formation water types and the initial source of formation water in the study area are comprehensively analyzed and discussed. The hydrogeological preservation conditions in the study area are firstly distinguished. Through the difference of salinity, daily water production and water-gas ratio between condensate water and liquid formation water, the water sample of TDS 10000mg/l is defined as condensate water, and the water sample of TDS (> 10000mg/l) is defined as formation water. The characteristics of formation water salinity of each stratum in the study area show that the stratum water salinity of the Upper Triassic is obviously higher than that of the Jurassic, the stratum water of the Upper Triassic is mainly brine, and the stratum water of the Jurassic is mainly brine. According to the analysis of the types of formation water in the study area, the main types of formation water in the study area are CaCl2 type, and a small number of MgCl2 type and Na HCO3 type. However, there are more Na2SO4 types in the Upper Jurassic, from the Upper Jurassic to the Xu2 member, and the water types are Na2SO4 type. The main cation in formation water is Na+, and the main anion is Cl-. The relationship between the cation content of formation water in different formations is Na+Ca 2+K+Mg 2+. The relationship between the anion content in formation water in Xu 2 member, Xu 4 member and Middle Jurassic member is Cl-HCO 3-SO 42-, and that in Upper Jurassic formation water is Cl-. The anions in the water are Cl-SO42-HCO3-. By comparing with the contents of trace elements in oceans, lakes and rivers, the formation water in the study area also shows obvious enrichment of trace elements Li, Sr, Ba, Br and Fe, indicating that the formation water in the study area has undergone a certain degree of evaporation and water-rock interaction, and the Xujiahe Formation is especially enriched in B. Based on the detailed geochemical characteristics of formation water and regional geological characteristics, the genesis of different types of formation water in the study area is analyzed. The results show that the formation of a small amount of high salinity Na HCO3 water in the second and fourth member of Xuzhou Formation is most likely to be related to the source rocks. Mesogenic CO2 is related; Middle Jurassic and Upper Jurassic Na HCO3, Na2SO4 are most likely to be primary continental formation water, and the second member of Xujia Formation Na2SO4 may be a mixture of CaCl2 and Na HCO3; the fourth member of Xujia Formation MgCl2 is more likely to be primary marine formation water, while the upper Jurassic MgCl2 is mainly from lower Jurassic. The high salinity Ca Cl_2 water of the Fuxujiahe Formation was mixed with the low salinity NaHCO_3 water of the Upper Jurassic. The Ca Cl_2 water of the Middle Jurassic and Upper Jurassic was mainly migrated from the high salinity formation water of the underlying Xujiahe Formation through faults. The relationship between freshwater evaporation curves and development curves shows that the formation water of Xu 2 and Xu 4 in the study area originates from seawater, and the evaporation degree of seawater is weak, which mainly shows the characteristics of low evaporation degree seawater. Characteristic analysis shows that the formation water in the study area is mainly composed of mixed genetic water of seawater and atmospheric water, and the upper Triassic formation water is mixed water. Compared with the Jurassic formation water, it is characterized by richer seawater. A small amount of the upper Triassic formation water shows obvious negative drift of delta 18O due to the influence of the exchange of formation water and CO2 isotope, showing the formation of atmospheric water. Jurassic formation water is mainly mixed water, and the middle Jurassic formation water is richer in seawater components than the upper Jurassic formation water. A few of the Jurassic formation water still retains the characteristics of atmospheric water. The analysis of the combination characteristics of the characteristic parameters, such as sodium chloride coefficient, desulfurization coefficient, carbonate equilibrium coefficient and magnesium chloride coefficient, shows that most of the formation water in the study area has the characteristics of high concentration and deep metamorphism. The sealing property of the Jurassic strata is worse than that of the Upper Jurassic, especially the formation water of Na_2SO_4 type, oil and gas. The condition of preservation is relatively poor, and the two and four strata are more closed, which is more conducive to oil and gas preservation.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.13
本文編號：2237801
[Abstract]:Formation and activity of formation water are closely related to the generation, migration and accumulation of oil and gas, formation, preservation and destruction of oil and gas reservoirs. Western Sichuan depression is a depression basin evolved from foreland basin since Late Triassic and deposited huge thickness of Late Triassic. In the Permian-Cretaceous strata, many sets of gas-bearing strata have been discovered, in which high-salinity formation water is ubiquitous. In geological history, the exchange of substance and energy between formation water and surrounding rocks and oil and gas is widespread, and the geochemical characteristics of formation water are the direct recorders of these reaction processes, containing a lot of oil and gas. Based on the formation water data of Xu 2, Xu 4, Middle Jurassic and Upper Jurassic, the basic geochemical characteristics of formation water in the study area are analyzed in detail. Combined with the geological background of the work area, the genesis of formation water types and the initial source of formation water in the study area are comprehensively analyzed and discussed. The hydrogeological preservation conditions in the study area are firstly distinguished. Through the difference of salinity, daily water production and water-gas ratio between condensate water and liquid formation water, the water sample of TDS 10000mg/l is defined as condensate water, and the water sample of TDS (> 10000mg/l) is defined as formation water. The characteristics of formation water salinity of each stratum in the study area show that the stratum water salinity of the Upper Triassic is obviously higher than that of the Jurassic, the stratum water of the Upper Triassic is mainly brine, and the stratum water of the Jurassic is mainly brine. According to the analysis of the types of formation water in the study area, the main types of formation water in the study area are CaCl2 type, and a small number of MgCl2 type and Na HCO3 type. However, there are more Na2SO4 types in the Upper Jurassic, from the Upper Jurassic to the Xu2 member, and the water types are Na2SO4 type. The main cation in formation water is Na+, and the main anion is Cl-. The relationship between the cation content of formation water in different formations is Na+Ca 2+K+Mg 2+. The relationship between the anion content in formation water in Xu 2 member, Xu 4 member and Middle Jurassic member is Cl-HCO 3-SO 42-, and that in Upper Jurassic formation water is Cl-. The anions in the water are Cl-SO42-HCO3-. By comparing with the contents of trace elements in oceans, lakes and rivers, the formation water in the study area also shows obvious enrichment of trace elements Li, Sr, Ba, Br and Fe, indicating that the formation water in the study area has undergone a certain degree of evaporation and water-rock interaction, and the Xujiahe Formation is especially enriched in B. Based on the detailed geochemical characteristics of formation water and regional geological characteristics, the genesis of different types of formation water in the study area is analyzed. The results show that the formation of a small amount of high salinity Na HCO3 water in the second and fourth member of Xuzhou Formation is most likely to be related to the source rocks. Mesogenic CO2 is related; Middle Jurassic and Upper Jurassic Na HCO3, Na2SO4 are most likely to be primary continental formation water, and the second member of Xujia Formation Na2SO4 may be a mixture of CaCl2 and Na HCO3; the fourth member of Xujia Formation MgCl2 is more likely to be primary marine formation water, while the upper Jurassic MgCl2 is mainly from lower Jurassic. The high salinity Ca Cl_2 water of the Fuxujiahe Formation was mixed with the low salinity NaHCO_3 water of the Upper Jurassic. The Ca Cl_2 water of the Middle Jurassic and Upper Jurassic was mainly migrated from the high salinity formation water of the underlying Xujiahe Formation through faults. The relationship between freshwater evaporation curves and development curves shows that the formation water of Xu 2 and Xu 4 in the study area originates from seawater, and the evaporation degree of seawater is weak, which mainly shows the characteristics of low evaporation degree seawater. Characteristic analysis shows that the formation water in the study area is mainly composed of mixed genetic water of seawater and atmospheric water, and the upper Triassic formation water is mixed water. Compared with the Jurassic formation water, it is characterized by richer seawater. A small amount of the upper Triassic formation water shows obvious negative drift of delta 18O due to the influence of the exchange of formation water and CO2 isotope, showing the formation of atmospheric water. Jurassic formation water is mainly mixed water, and the middle Jurassic formation water is richer in seawater components than the upper Jurassic formation water. A few of the Jurassic formation water still retains the characteristics of atmospheric water. The analysis of the combination characteristics of the characteristic parameters, such as sodium chloride coefficient, desulfurization coefficient, carbonate equilibrium coefficient and magnesium chloride coefficient, shows that most of the formation water in the study area has the characteristics of high concentration and deep metamorphism. The sealing property of the Jurassic strata is worse than that of the Upper Jurassic, especially the formation water of Na_2SO_4 type, oil and gas. The condition of preservation is relatively poor, and the two and four strata are more closed, which is more conducive to oil and gas preservation.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.13
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