塔中地区碳酸盐岩高含量二氧化碳的产生及研究意义

塔中碳酸盐岩天然气样品中CO_2含量及其碳同位素值的分析表明,CO_2既有有机成因也有无机成因,而烃气则全为有机成因。样品对比表明,塔中碳酸盐岩天然气中的CO_2含量一般在5%以下,而高含量的CO_2则是酸化压裂时由人工注入的强酸与碳酸盐岩地层反应产生的。酸化压裂产生的CO_2含量与注入地层的酸量正相关,与求产时间负相关;据此建立了最高CO_2含量—酸量—时间相关关系图版。酸化压裂可使气样中的CO_2含量增加,但对N_2和H_2S的含量没什么影响。增高的CO_2会使和CO_2含量有关的参数受到影响,但不会影响和CO_2含量无关的研究参数。对天然气分析数据的使用提出了相关建议。

Genesis and Study Significance of High CO2 Content in Carbonate Rocks in Tazhong Area, Tarim Basin

The CO_2 content and carbon isotopic values are analyzed for natural gas samples from carbonate rocks in Tazhong area.It is indicated that the CO_2 gas in some gas samples is organic in origin and the one in other gas samples is inorganic but the hydrocarbon gas is al organic in origin.By comparing with four types of gas samples,it is improved that the CO_2 content of natural gas from Tazhong carbonate rocks is general y less than 5%while the CO_2 whose content is high is generated by acid fracturing.The CO_2 content in the gas samples generated by acid fracturing has a positive correlation to the acid amount and keeps a negative correlation to the production time.According to the analysis data,a correlation chart of maximum CO_2 content-acid amount-production time is established.Acid fracturing may bring in increasing the CO_2 content in the gas samples but less affects on the N_2 and H_2S content.The increasing CO_2 can affect the parameters related with CO_2content but cannot affect those parameters which have no relation to CO_2 content.Some suggestions how to use the analysis data of gas samples are final y put forward.