CAJ | 학술논문

通过对塔里木盆地沙雅隆起阿克库勒凸起东部塔深1井寒武系白云岩岩石学特征及成岩成因分析,影响塔深1井寒武系地层流体改变主要成岩有准同生期、埋藏期和后期热液改造期等.塔深1井寒武系白云岩及充填孔、洞、缝内方解石的氧、碳、锶同位素地球化学特征表明:准生期白云岩δ~(13)C_(PDB)值(0.9‰～1.8‰)偏正、δ~(18)C_(PDB)值(-10.1‰～-4.2‰)偏负反映准同生期泥微晶白云石成因属于高盐度的海水使得碳酸盐泥发生白云石化;埋藏期白云岩碳、氧随重结晶作用加强,白云岩晶粒由细向粗变化值随埋深增加,由于同位素分馏作用而偏负,δ~(18)C_(PDB)值(-10.02‰～-5.7‰)呈明显的下降,但δ~(13)C_(PDB)值(-1.4‰～0‰)组成变化不大;后期热液白云岩在热液作用下δ~(18)C_(PDB)值普遍低于-10‰(δ~(18)C_(PDB)/‰-13.1～-9.4,δ~(13)C_(PDB)/‰-2～-0.647);基质方解石δ~(18)C_(PDB)值为-10.1‰～-10.13‰,δ~(13)C_(PDB)值为-1.48‰～-1.62‰;充填孔洞缝粗-巨晶方解石δ~(18)C_(PDB)值为-10.89‰～-14.28‰,δ~(13)C_(PDB)值为-2‰～-3.09‰,反映准同生期→埋藏期→后期热液晶粒大小由泥微晶→细晶→中晶→粗晶氧碳同位素值逐渐变小偏负,据~(87)Sr/~(86)Sr(0.707 284～0.746 888)值均远高于现今海洋中海水的锶同位素组成(0.708)及围岩的锶同位素(0.707 284),说明鞍形白云石以及方解石结晶时的孔隙流体不是残余在岩石孔隙中的同生期海水,而是外来的富含锶的流体,也就是深部热液流体.渗透回流白云石化、埋藏白云石化和高温热液白云石化等特征表明白云岩形成于超盐度、埋藏和高温热液等3种不同的环境,因此影响储层形成与分布,从而影响对白云岩的勘探.
통과대탑리목분지사아륭기아극고륵철기동부탑심1정한무계백운암암석학특정급성암성인분석,영향탑심1정한무계지층류체개변주요성암유준동생기、매장기화후기열액개조기등.탑심1정한무계백운암급충전공、동、봉내방해석적양、탄、송동위소지구화학특정표명:준생기백운암δ~(13)C_(PDB)치(0.9‰～1.8‰)편정、δ~(18)C_(PDB)치(-10.1‰～-4.2‰)편부반영준동생기니미정백운석성인속우고염도적해수사득탄산염니발생백운석화;매장기백운암탄、양수중결정작용가강,백운암정립유세향조변화치수매심증가,유우동위소분류작용이편부,δ~(18)C_(PDB)치(-10.02‰～-5.7‰)정명현적하강,단δ~(13)C_(PDB)치(-1.4‰～0‰)조성변화불대;후기열액백운암재열액작용하δ~(18)C_(PDB)치보편저우-10‰(δ~(18)C_(PDB)/‰-13.1～-9.4,δ~(13)C_(PDB)/‰-2～-0.647);기질방해석δ~(18)C_(PDB)치위-10.1‰～-10.13‰,δ~(13)C_(PDB)치위-1.48‰～-1.62‰;충전공동봉조-거정방해석δ~(18)C_(PDB)치위-10.89‰～-14.28‰,δ~(13)C_(PDB)치위-2‰～-3.09‰,반영준동생기→매장기→후기열액정립대소유니미정→세정→중정→조정양탄동위소치축점변소편부,거~(87)Sr/~(86)Sr(0.707 284～0.746 888)치균원고우현금해양중해수적송동위소조성(0.708)급위암적송동위소(0.707 284),설명안형백운석이급방해석결정시적공극류체불시잔여재암석공극중적동생기해수,이시외래적부함송적류체,야취시심부열액류체.삼투회류백운석화、매장백운석화화고온열액백운석화등특정표명백운암형성우초염도、매장화고온열액등3충불동적배경,인차영향저층형성여분포,종이영향대백운암적감탐.
The analysis of petrological characteristics and diagenesis of Cambrian dolomite from well Tashen 1 in eastern Akekule Salient of Shaya Uplift,Tarim Basin,revealed that. The varia-tion of Cambrian-strata-fluid in well Tashen 1 was mainly affected by pencontemporaneous peri-od,burial period,late hydrothermal-transformation period and so on. Based on the study of iso-topes of oxygen, carbon and stontium and geochemical characteristic showed following features. The δ~(18)O_(PDB)‰ in pencontemporaneous period dolomite varied from -10. 1 to -4.2, and the δ~(13)O_(PDB)/‰ varied from 0. 9 to 1.8. The δ~(13)O_(PDB) was partial positive and the δ~(18)O_(PDB) partial nega-tive,indicating that the formation of pencontemporaneous period microcrystalline dolomite is duo to the dolomitization of carbonate mud,and the dolomitization was a result of high-salinity seawa-ter. In burial environment, the δ~(18)O_(PDB)/‰ 000 in burial-period dolomite varied from -10. 02 to -5.7,and the δ~(18)O_(PDB)/‰ from -1.4 to 0. The stable isotopes of carbon and oxygen enhanced with recrystallization, and the dolomite grains changed from fine to coarse grained with increasing depth. Due to isotope fractionation, the δ~(18)O_(PDB) showed a significant decrease, and therefore,the value was partial negative. But the composition of δ~(18)O_(PDB) showed a little change. The δ~(18)O_(PDB)/‰ in late hydrothermal-transformation-period dolomite varied from -13.1 to -9.4. And the δ~(13)O_(PDB)/‰ from -2 to -0. 647. Under hydrothermal condition,the δ~(18)O_(PDB)/‰ values were gen-erally lower than -10%0. The δ~(18)O_(PDB)/‰ in matrix calcite varied from -10.1 to -10. 13,and the δ~(13)O_(PDB)/‰ varied from -1.48 to -1.62. The δ~(18)O_(PDB)/‰ filled in the coarse-grained calcite and megacrysts calcite varied from -10.89 to -14.28,and δ~(13)O_(PDB)>/‰ varied from -2 to -3.09. It was indicated that, with the time from pencontemporaneous period to burial period and to late hy-drothermal-transformation period,the grain size varied from mud microcrystalline to fine grain to medium grain to coarse grain. Oxygen and carbon isotope value were decreased to partial negative. The values 0.707 284～0.746 888 of ~(87)Sr/~(86)Sr were higher than that of present ocean water (~(87)Sr/~(86)Sr=0. 708) and surrounding rock(~(87)Sr/~(86)Sr=0. 707 284). The pore fluid in saddle-shaped dolomite and calcite crystallization,was not the pencontemporaneous period seawater remained in the pores of rock,but the outside strontium-rich fluid,that is,the deep hydrothermal fluids. In the environment of super salinity, burial and hydrotherm with high temperature, the dolostone formed finally through three types of dolomitization,including seepage reflux dolomitization, burial dolo-mitization and high-temperature hydrothermal dolomitization,which influenced the formation and distribution of reservoirs,and consequently influenced the future exploration of oil and gas.