论文部分内容阅读
原油黏度、密度通常随油藏埋深的增加呈下降趋势。基于这种认识,勘探阶段只对部分油藏进行原油取样分析,其他油藏通过插值或借用。最新研究发现,南海东部浅层油藏原油性质不符合这一规律,有时深度相邻的油藏原油性质相差较大。生物降解分析发现,原油性质较差的油藏生物降解严重,甚至正构烷烃几乎全部降解。这种现象在南海东部普遍存在,给储量计算、开发方案编制造成较大风险。进一步研究表明,浅层油藏原油性质主要受生物降解的控制,生物降解在低于80℃的有氧环境下普遍存在,因此,南海东部埋深较浅的油藏原油性质普遍受生物降解的影响;在浅层油藏中,底水油藏生物降解更为严重,因此原油性质普遍较差;而边水油藏水动力较弱,受生物降解影响较轻,因此原油保存较好。鉴于浅层油藏原油性质的特殊变化规律,主力油藏一定要单独取样,取样点尽量选在构造高部位,减轻生物降解的影响;开发方案选值时,要同时考虑油藏类型、物性好坏等因素。
Crude oil viscosity, density usually decreases with the increase of buried depth. Based on this understanding, some oil reservoirs are only sampled and analyzed during the exploration stage, and other reservoirs are interpolated or borrowed. The latest study found that the nature of the crude oil in the shallow reservoirs in the eastern South China Sea does not comply with this law, and sometimes the depth of adjacent reservoirs of crude oil properties vary greatly. Biodegradability analysis found that reservoirs with poorer crude oil biodegraded severely, even n-alkanes degrade almost completely. This phenomenon is widespread in the east of the South China Sea, posing a greater risk to reserves calculation and development planning. Further studies show that the properties of crude oil in shallow reservoirs are mainly controlled by biodegradation, and biodegradation is ubiquitous under an aerobic environment below 80 ℃. Therefore, the crude oil properties of shallow depths in the eastern South China Sea are generally biodegraded In the shallow reservoirs, the bottom water reservoir is more biodegradable, so the properties of the crude oil are generally poorer. However, the water in the edge water reservoir is weaker and less affected by biodegradation, so the crude oil is well conserved. In view of the special variation of crude oil properties in shallow reservoirs, the main reservoirs must be sampled separately and the sampling points should be selected as high as possible to reduce the impact of biodegradation. When selecting a development plan, the reservoir type and physical properties should be taken into consideration Bad and other factors.