Characteristics of hydrothermal activity in the Tarim Basin and its reworking effect on carbonate reservoirs

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• 作者：Wei Liu^a ; ^b ; ^{liuwei086@petrochina.com.cn} ; Qingyu Huang^b ; Kun Wang^b ; Shuyuan Shi^b ; Hua Jiang^b
• 关键词：Tarim Basin ; Early Palaeozoic ; Hydrothermal ; Carbonate ; Reservoir ; Dolomitization ; CO2 ; Diagenesis ; Dissolution
• 刊名：Natural Gas Industry B
• 出版年：2016
• 出版时间：May 2016
• 年：2016
• 卷：3
• 期：3
• 页码：202-208
• 全文大小：2363 K
• 卷排序：3

文摘

Hydrothermal activity is common in the Tarim Basin. In this paper, petrologic and geochemical features of the hydrothermal products in the carbonate rocks in this basin were analyzed so as to figure out the effect of hydrothermal activity on the Lower Palaeozoic carbonate reservoirs in this area. It is shown that the hydrothermal fluids in the Tarim Basin are generally high in CO2 content, but very low in Mg2+ content. Then, the reworking effect of hydrothermal activity on reservoir was further discussed. It is indicated that the component of hydrothermal fluid is the deciding factor for the reworking of reservoirs. The study provided the following findings. Firstly, hydrothermal fluid is rich in CO2. Dissolution is intense in the vicinity of fracture zones and dissolved pores of different sizes are developed. Therefore, small-scale high-quality reservoirs with good porosity and permeability are formed. Secondly, hydrothermal fluid itself is low in magnesium content and some additional magnesium can be produced from Cambrian dolomites by means of dissolution, but the scale of hydrothermal dolomitization is small. Thirdly, the hydrothermal fluids rich in CO2 form high-quality dissolved vug typed reservoirs by means of dissolving surrounding rocks and their distribution are controlled by faulting. Fourthly, the saddle-like dolomite with hydrothermal origin fills dissolved vugs. Furthermore, the hydrothermal activity in the vicinity of faults results in the recrystallization or excessive growth of dolomite crystal, blocking existed pores, which is a type of destructive diagenesis as a whole. The study results can provide a reference for carbonate reservoir prediction of deep basin.