旅大27-2油田地层水化学特征及与油气保存的关系

Chemical Characteristics of Formation Water and its Relationship with Oil and Gas Preservation in LD27-2 Oilfield

旅大27-2油田馆陶组和东营组地层水矿化度较高,以CaCl_(2)水型为主。根据地层水化学分特征,分析主导阴阳离子成因,计算出化学参数,分析其与油气聚集的关系。研究表明:富含Cl^(-)、Na^(+)的地层水成因主要与地下岩盐的溶解有关,水-岩的相互作用主要为斜长石的钠长石化,从而导致地层水中Ca^(2+)的富集。脱硫酸作用使油田SO_(4)^(2-)离子含量很低,随着井深的增加,各项离子化学参数纵向上比较稳定,均反映该区域地层水处于较停滞的还原状态,地层水封闭好,水-岩作用强,油藏没有受到外界破坏且整体显示封闭条件较好。

The formation water of Guantao Formation and Dongying Formation in LD 27-2 oilfield was mainly CaCl_(2) water type with high salinity. According to the chemical characteristics of formation water, the genesis of cation and anion was analyzed. Calculating the chemical parameters, the relationship between them and hydrocarbon accumulation was analyzed. Analysis showed that the genesis of formation water rich in Cl^(-)and Na^(+) was mainly related to the dissolution of underground rock salt, and the water rock interaction was mainly albitization of plagioclase, which leaded to the enrichment of Ca^(2+) in formation water. The content of SO_(4)^(2-)ion in oil field was very low due to desulfurization. With the increase of depth, the chemical parameters of various ions were relatively stable in the longitudinal direction. It reflected that the formation water in this area was in a relatively stagnant reduction state. The formation water was well sealed, and the water rock interaction was strong. So the reservoir was not damaged by the outside, and the overall sealing conditions were good.