辽东湾坳陷油田水化学特征与油气运聚的关系

基于实际测试资料,统计分析了辽东湾坳陷油田水的水型、矿化度和化学系数的纵、横向变化特征;并探讨了油田水化学特征与油气运聚的关系。研究表明,研究区油田水以NaHCO3型为主;矿化度随埋深先增大后减小,垂向上分为三个带:近地表蒸发浓缩带、越流压滤浓缩带、泥岩压实排水淡化带;常规离子组成中Na++K+和Cl-占绝对优势。在地层压实排水离心流过程中,地层水明显受泥岩压实排水淡化作用的影响,矿化度较低;地层水在离心流运移过程中不断越流浓缩,矿化度逐渐增大,油气垂向上沿油源断层向上运移,在低凸起、断裂带、砂体等近地表蒸发浓缩带聚集成藏。

Hydrochemical properties of oilfield water and its relationship with oil and gas migration and accumulation in the Liaodong bay depression

Based on practical test data ,this paper discusses the vertical and lateral characteristics of oilfield water type ,salinity ,salt-ionic constituent and chemical coefficient in the Liaodong bay depression and the relationship between hydrochemistry and oil and gas migration and accumulation. The study results show that the type of oilfield water in the area is predominantly NaHCO3 with its salinity increasing and then decreasing with burial-depth , from the shallow to the deep part is divided into three zones,near surface evaporative concentration zone; concentration zone by cross-formational flow; mudstone compaction and dehydration fresh zone. The general ions are high contents of Na+ K and Cl-. During the process of centrifugal flow, the formation water ,affected by the desalting of compaction-released water, has low mineralization of formation water. However ,the formation water concentrated and its mineralizaion increased gradually during the process of centrifuge over flow. The hydrocarbon migrates up along the fault of source rock vertically and accumulates in medium-shallow traps.