川中磨溪—高石梯地區(qū)震旦系燈影組白云巖成因及與儲層的關(guān)系
發(fā)布時間：2018-08-26 21:18
【摘要】：白云巖的成因、產(chǎn)狀和分布等方面的研究是沉積盆地內(nèi)白云巖型油氣勘探的地質(zhì)基礎(chǔ)。四川盆地震旦系燈影組表現(xiàn)為大面積分布的白云巖,向東至盆地外圍湖北三峽一帶逐漸過渡為灰?guī)r。大面積分布的厚層塊狀白云巖是燈影組儲層發(fā)育的載體,燈影組儲層的孔隙演化與其白云石化作用有著密不可分的關(guān)系。對于四川盆地震旦系燈影組白云巖的成因問題,一直來都是地質(zhì)學(xué)家們爭論的熱點問題。因此,在對其儲層形成機理研究過程中,需要從沉積學(xué)、巖石學(xué)以及地球化學(xué)等多方面對四川盆地內(nèi)燈影組白云巖的成因進行研究。 本論文在總結(jié)國內(nèi)外相關(guān)研究技術(shù)及成果的基礎(chǔ)上,結(jié)合研究區(qū)地質(zhì)背景,主要采用巖礦鑒定技術(shù)以及多種地球化學(xué)分析技術(shù)(包括碳氧同位素、鍶同位素、稀土元素、微量元素和包裹體等分析方法),對四川盆地川中磨溪-高石梯地區(qū)震旦系燈影組白云巖成因進行了較為深入的研究,并簡要探討了白云巖化與儲層的關(guān)系。 根據(jù)野外與巖心觀察、薄片鑒定等研究,按照結(jié)構(gòu)-成因?qū)δハ?高石地區(qū)燈影組白云巖類型及特征進行了較為系統(tǒng)的研究,認為該套地層主要發(fā)育藍藻細菌白云巖、顆粒白云巖、晶粒白云巖及角礫白云巖四種類型,其中晶粒白云巖是重結(jié)晶作用的產(chǎn)物,角礫白云巖(包括風(fēng)化殘余角礫巖白云巖、巖溶角礫巖白云巖)是構(gòu)造作用和表生巖溶作用共同影響下的產(chǎn)物。而藍藻細菌白云巖、顆粒白云巖則是燈影組地層沉積時期所形成,保留了早期近地表環(huán)境下巖石的特征,這些特征為分析燈影組白云巖的成因提供了地質(zhì)基礎(chǔ)。 碳、氧同位素分析表明,經(jīng)受同位素分餾、地溫及后期成巖作用改造較弱的巖石,其碳、氧同位素最為接近燈影組海水沉積時的海水碳、氧同位素值；而受后期成巖作用改造較為強烈的巖石,其氧同位素明顯偏負、碳同位素略微有所偏負。鍶同位素主要受到幔源(Sr86)和陸源(Sr87)的控制,其燈影組巖石鍶同位素明顯偏高,說明成巖流體中有放射性鍶(Sr87)的混入。稀土元素分析顯示,燈影組白云巖缺失海水Ce和Eu的負異常,而顯示出明顯的Ce和Eu正異常特征。此外,受成巖作用改造較弱、保存原始沉積組構(gòu)、沉積構(gòu)造、富含藍藻細菌的巖石,其Mn和Fe含量相對較低。這一系列地化分析資料可以直接或間接證明四川盆地?zé)粲敖M白云巖是在早期近地表環(huán)境下形成的,但后期成巖作用使得巖石碳氧同位素、鍶同位素、微量元素、稀土元素等發(fā)生了變化。 在近地表環(huán)境下,由于動力學(xué)障礙(SO42-的阻礙、Mg2+的束縛、CO32-濃度和活動性低)的存在,白云石是不能夠從海水中直接沉淀的。除此之外,從結(jié)晶學(xué)和礦物學(xué)上講,早期海水纖狀白云石膠結(jié)物只能是交代文石和鎂方解石的產(chǎn)物。四川盆地?zé)粲敖M早期沉積物是富藍藻細菌的碳酸鹽物質(zhì),在硫酸鹽還原細菌的作用下,地層中的藍藻細菌席發(fā)生生物降解作用,導(dǎo)致沉積物中孔隙流體(當時的海水)的SO42-減少,增加了流體中CO32-的濃度及活動性,并使Mg2+從海水孔隙水和藍藻細菌席中釋放出來,從而克服白云石形成的動力學(xué)障礙,促進白云石化作用的進行。因此,結(jié)合上述燈影組白云巖地化資料及有機成因白云石化過程,證明燈影組白云巖是在早期近地表環(huán)境下交代而成。同時,白云巖化作用為白云巖儲層發(fā)育提供了先決條件,但沉積、成巖、構(gòu)造作用才是形成白云巖儲層的關(guān)鍵因素。
[Abstract]:The genesis, occurrence and distribution of dolomite are the geological basis of dolomite-type oil and gas exploration in sedimentary basins. The Dengying Formation of Sinian in Sichuan Basin is characterized by large-area distribution of dolomite, which is gradually transformed into limestone from east to the periphery of the basin in the Three Gorges area of Hubei Province. The pore evolution of Dengying Formation reservoir is closely related to its dolomitization. The genesis of Dolomite in Dengying Formation of Sinian System in Sichuan Basin has always been a hot issue debated by geologists. The genesis of dolomite in the Dengying Formation in the Sichuan basin is studied in terms of chemistry and many other aspects.
On the basis of summarizing the related research technology and achievements at home and abroad, combined with the geological background of the study area, this paper mainly uses rock and mineral identification technology and a variety of geochemical analysis techniques (including carbon and oxygen isotopes, strontium isotopes, rare earth elements, trace elements and inclusions, etc.) to study the earthquakes in the Moxi-Gaoshiting area of Sichuan Basin. The genesis of dolomite in Dengying Formation of the Dengying Formation is studied in depth and the relationship between dolomitization and reservoir is briefly discussed.
Based on field observation, core observation and thin section identification, the dolomite types and characteristics of Dengying Formation in Moxi-Gaoshi area are systematically studied according to their structure-genesis. It is considered that the dolomite is mainly composed of cyanobacterial dolomite, granular dolomite, granular dolomite and breccia dolomite. The product of crystallization, breccia dolomite (including weathered residual breccia dolomite, karst breccia dolomite) is the product of both tectonic and epigenetic karstification. Cyanobacterial dolomite and granular dolomite were formed during the deposition of the Dengying Formation, retaining the characteristics of rocks in the early near-surface environment. It provides geological basis for analyzing the genesis of dolomite in the Dengying Formation.
Carbon and oxygen isotope analysis shows that the rocks weakly reformed by isotope fractionation, geotemperature and later diagenesis are the closest to the carbon and oxygen isotope values of seawater deposited by the Dengying Formation, while the rocks strongly reformed by later diagenesis are obviously negative in oxygen isotope and slightly negative in carbon isotope. Strontium isotopes are mainly controlled by mantle (Sr86) and terrestrial (Sr87). Strontium isotopes of the Dengying Formation rocks are obviously high, indicating that there is a mixing of radioactive strontium (Sr87) in the diagenetic fluid. REE analysis shows that the Dengying Formation dolomite lacks negative Ce and Eu anomalies in the seawater and shows obvious positive Ce and Eu anomalies. This series of geochemical data can directly or indirectly prove that the Dolomite of Dengying Formation in Sichuan Basin was formed in the early near-surface environment, but the later diagenesis caused the carbon and oxygen isotopes and strontium isotopes of the rocks. Trace elements and rare earth elements have changed.
In the near-surface environment, dolomite can not be precipitated directly from seawater due to the existence of kinetic barriers (SO42-hindered, Mg2+ bound, CO32-concentration and low activity). In addition, the early marine fibrous dolomite cements can only be the products of metasomatic aragonite and magnesia calcite in terms of crystallography and mineralogy. The early sediments of the Dengying Formation were carbonate substances of cyanobacteria. Under the action of sulfate-reducing bacteria, the cyanobacteria mat in the formation biodegraded, resulting in the decrease of SO42-in the pore fluid (then seawater), increasing the concentration and activity of CO32-in the fluid, and making Mg2+ from seawater pore water and cyanobacteria fine. Therefore, combined with the geochemical data of the Dengying Formation dolomite and the process of organic dolomitization, it is proved that the Dengying Formation dolomite was formed in the early near-surface environment. Breeding provides a prerequisite, but sedimentation, diagenesis and tectonism are the key factors for dolomite reservoir formation.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.13;P588.245
本文編號：2206184
[Abstract]:The genesis, occurrence and distribution of dolomite are the geological basis of dolomite-type oil and gas exploration in sedimentary basins. The Dengying Formation of Sinian in Sichuan Basin is characterized by large-area distribution of dolomite, which is gradually transformed into limestone from east to the periphery of the basin in the Three Gorges area of Hubei Province. The pore evolution of Dengying Formation reservoir is closely related to its dolomitization. The genesis of Dolomite in Dengying Formation of Sinian System in Sichuan Basin has always been a hot issue debated by geologists. The genesis of dolomite in the Dengying Formation in the Sichuan basin is studied in terms of chemistry and many other aspects.
On the basis of summarizing the related research technology and achievements at home and abroad, combined with the geological background of the study area, this paper mainly uses rock and mineral identification technology and a variety of geochemical analysis techniques (including carbon and oxygen isotopes, strontium isotopes, rare earth elements, trace elements and inclusions, etc.) to study the earthquakes in the Moxi-Gaoshiting area of Sichuan Basin. The genesis of dolomite in Dengying Formation of the Dengying Formation is studied in depth and the relationship between dolomitization and reservoir is briefly discussed.
Based on field observation, core observation and thin section identification, the dolomite types and characteristics of Dengying Formation in Moxi-Gaoshi area are systematically studied according to their structure-genesis. It is considered that the dolomite is mainly composed of cyanobacterial dolomite, granular dolomite, granular dolomite and breccia dolomite. The product of crystallization, breccia dolomite (including weathered residual breccia dolomite, karst breccia dolomite) is the product of both tectonic and epigenetic karstification. Cyanobacterial dolomite and granular dolomite were formed during the deposition of the Dengying Formation, retaining the characteristics of rocks in the early near-surface environment. It provides geological basis for analyzing the genesis of dolomite in the Dengying Formation.
Carbon and oxygen isotope analysis shows that the rocks weakly reformed by isotope fractionation, geotemperature and later diagenesis are the closest to the carbon and oxygen isotope values of seawater deposited by the Dengying Formation, while the rocks strongly reformed by later diagenesis are obviously negative in oxygen isotope and slightly negative in carbon isotope. Strontium isotopes are mainly controlled by mantle (Sr86) and terrestrial (Sr87). Strontium isotopes of the Dengying Formation rocks are obviously high, indicating that there is a mixing of radioactive strontium (Sr87) in the diagenetic fluid. REE analysis shows that the Dengying Formation dolomite lacks negative Ce and Eu anomalies in the seawater and shows obvious positive Ce and Eu anomalies. This series of geochemical data can directly or indirectly prove that the Dolomite of Dengying Formation in Sichuan Basin was formed in the early near-surface environment, but the later diagenesis caused the carbon and oxygen isotopes and strontium isotopes of the rocks. Trace elements and rare earth elements have changed.
In the near-surface environment, dolomite can not be precipitated directly from seawater due to the existence of kinetic barriers (SO42-hindered, Mg2+ bound, CO32-concentration and low activity). In addition, the early marine fibrous dolomite cements can only be the products of metasomatic aragonite and magnesia calcite in terms of crystallography and mineralogy. The early sediments of the Dengying Formation were carbonate substances of cyanobacteria. Under the action of sulfate-reducing bacteria, the cyanobacteria mat in the formation biodegraded, resulting in the decrease of SO42-in the pore fluid (then seawater), increasing the concentration and activity of CO32-in the fluid, and making Mg2+ from seawater pore water and cyanobacteria fine. Therefore, combined with the geochemical data of the Dengying Formation dolomite and the process of organic dolomitization, it is proved that the Dengying Formation dolomite was formed in the early near-surface environment. Breeding provides a prerequisite, but sedimentation, diagenesis and tectonism are the key factors for dolomite reservoir formation.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P618.13;P588.245
【參考文獻】
相關(guān)期刊論文 前10條
1 鄭榮才,陳洪德;川東黃龍組古巖溶儲層微量和稀土元素地球化學(xué)特征[J];成都理工學(xué)院學(xué)報;1997年01期
2 雷懷彥,朱蓮芳;四川盆地震旦系白云巖成因研究[J];沉積學(xué)報;1992年02期
3 王興志,穆曙光,方少仙,侯方浩,黃繼祥;四川資陽地區(qū)燈影組灘相沉積及儲集性研究[J];沉積學(xué)報;1999年04期
4 方少仙,侯方浩,董兆雄;上震旦統(tǒng)燈影組中非疊層石生態(tài)系蘭細菌白云巖[J];沉積學(xué)報;2003年01期
5 曹瑞驥;我國中新元古代地層研究中若干問題的探討[J];地層學(xué)雜志;2000年01期
6 黃汲清;中國大地構(gòu)造特征的新研究[J];中國地質(zhì)科學(xué)院院報;1984年02期
7 張學(xué)豐;劉波;蔡忠賢;胡文tD;;白云巖化作用與碳酸鹽巖儲層物性[J];地質(zhì)科技情報;2010年03期
8 劉鴻允,董榕生,李建林,楊彥均;論震旦系劃分與對比問題[J];地質(zhì)科學(xué);1980年04期
9 黃志誠,陳智娜,劉燕,楊守業(yè);中國南方燈影峽期海洋碳酸鹽巖原始δ~(13)C和δ~(18)O組成及海水溫度[J];古地理學(xué)報;1999年03期
10 李英強;何登發(fā);文竹;;四川盆地及鄰區(qū)晚震旦世古地理與構(gòu)造—沉積環(huán)境演化[J];古地理學(xué)報;2013年02期
，本文編號：2206184
本文鏈接：http://sikaile.net/kejilunwen/shiyounenyuanlunwen/2206184.html
最近更新
教材專著
