西南油气田含锂气田水资源调查分析

截至2020年底,国内锂资源供应对外依存度高达70%。据统计,中国石油西南油气田公司(以下简称西南油气田)各气田在开发过程中普遍产水,目前西南油气田拥有生产井1 900余口,其中超80%的生产井产水,2020年常规气气田累计产水超120×10⁸ m³。据研究报道,气田水与油气等烃类物质共同经历了漫长的油气成藏阶段,通常含有更多的微量元素,甚至部分锂资源含量高于盐湖卤水。通过气田水取样分析证实,西南油气田17口井气田水中锂离子质量浓度最高达131.6 mg/L,约50%取样井气田水中锂离子含量高于最低工业品位,同时还含有较为丰富的溴、钾等伴生资源。通过对重点井气田水跟踪评价证实西南油气田气田水锂、溴资源长周期稳定性较好,此外,西南油气田地层水资源丰富,3处重点区块地层水储量达13.3×10⁸ m³,初步估算了3处区块锂资源(以Li₂CO₃计)总价值超3 100亿元,具有较大的开发利用价值。

Investigation and analysis of lithium-containing gas field water resource in Southwest Oil and Gas Field

ObjectiveBy the end of 2020, the domestic lithium resources supply depending on external is as high as 70%. According to statistics, the gas fields of PetroChina Southwest Oil & Gasfield Company(Hereinafter referred to as Southwest Oil and Gas Field) generally produce water during development. At present, Southwest Oil and Gas Field has more than 1 900 production wells, of which more than 80% produce water. In 2020, the cumulative water production of conventional gas fields had exceeded 12×10⁹ m³. According to previous research reported, the gas field water, together with hydrocarbons such as oil and gas, has gone through a long period of hydrocarbon accumulation, and often contains more trace elements, especially for lithium content in some gas fields water, which is higher than in salt lake brine. Further sampling found that the lithium ion content in gas fields water of 17 wells in Southwest Oil and Gas Field was as high as 131.6 mg/L, and about 50% of the gas fields water of sampling wells had a higher lithium ion content than the lowest industrial grade, and also contained relatively abundant bromine, potassium and other associated resources. The follow-up evaluation of gas fields water in key wells confirms that the long-term stability of lithium and bromine resources in gas fields is relatively good. In addition, the Southwest Oil and Gas Field is rich in formation water resources, with the reserves of formation water in the three key blocks reaching 1.33 billion cubic meters. It is preliminarily estimated that the total potential value of lithium resources (calculated as Li₂CO₃) in the three blocks exceeds 310 billion yuan, which has a great value of development and utilization.