靖边气田相对富水层的识别、分布及成因研究

靖边气田投产井产量低、递减快,部分井有地层水产出,不同区域的生产井产水量差异大。通过对气藏地层水特征、识别方法、地层水水源、地层水演化和影响气水分布地质因素的研究,对地层水的形成机理、分布规律、分布模式等有了较深入的认识。研究表明,气藏“相对富水区”主要分布在气田西部,呈块状或透镜状形式分布,多数以气水层共存为特点。地层水是在气排水阶段中保存在孔隙中的束缚水或因气体驱替能量有限而残存的部分可动水。在部分井区由于储层条件变化、局部致密带的形成而造成孔隙中水未受到天然气的大规模排驱而残留了大量的地层水,形成“相对富水区”。尽管气井产水对气田的整体开发与正常生产影响不大,但研究气藏的产水原因对今后生产管理和气藏的高效合理开发具有一定的现实意义。

Recognition,distribution and genesis of the water-rich strata in the Jingbian Gas Field

The Mawu gas pool within the Jingbian Gas Field lies in the central part of the Ordos Basin.The integration of genesis,evolution and distribution shows that no well-defined gas-water interface has been observed in the Mawu gas pool.The "relative water-rich areas" appear as masses or lenses chiefly in the western part of the gas field,characteristic of the co-existence of gas beds and water beds.The existing formation water in the Mawu-1 stratal pores is believed to be the bound water preserved in the pores during the migration of natural gas,or the relict flowing water due to the(deficiency) of gas energy.Reservoir variations and the formation of local dense zones in some parts or well areas permit the preservation of abundant formation water and thus the formation of the "relative water-rich areas".Although the water production in the course of gas pool exploitation tends to be related to the regional distribution of the "relative water-rich areas",it only has limited effects on the overall development of the gas pool in the study area.