某些非背斜圈闭型油气田上方的汞异常特征

本文介绍了三个非背斜圈闭型油气田上方进行汞量测量的试验结果,油层埋深一般在1200—3000m之间。分别属岩性圈闭、断块圈闭和岩性一断层圈闭型油气田,所用测量方法包括负压法壤中气汞量测量、累积吸附法壤中气汞量测量、土壤总汞测量、土壤吸附汞测量和水中汞量测量等。试验结果表明,各种方法在油气田上方均有清晰的异常显示。其异常特征与金属矿床上的汞气异常有其相似性。异常形态和空间分布,主要取决于导气构造的特性。汞气异常和电性异常与油气藏的关系进行了类比。这两种方法的异常有时与油气藏在地表的投影位置吻合,有时分别偏离一定距离,进一步证明了构造形态对异常的影响,并推断根据汞气异常和电性异常的特征,有可能追索油气藏的位置。

CHARACTERISTICS OF MERCURY ANOMALIES OVERSOME NONANTICLINAL CONFNED TYPE OIL ANDGAS FIELDS

Results of mercury survey test conducted over three nonanticlinal confinedtype oil and gas fields are reported in this paper. The oil-bearing reservoirs areusually buried 1200-3000m below the surface, pertaining respectively to oil andgas field of lithological confinement, that of fault block confinement and that oflithological-faulting confinement. The techniques employed include such means asdetermining gaseous mercury in soil all by negative pressure method and accu-mulative adsorption method, total mercury content in soil, adsorbed mercury insoil and mercury in water. The test results indicate that the methods used alldisplay distinct anomalies over the oil and gas fields, with their characteristicsanalogous to those of mercury vapour anomalies over metallic ore deposits. Theshape and spatial distribution of these anomalies depend largely on properties ofvapour-leading structures.The mercury vapour anomaly and electrical anomaly are contrasted relativeto oil and gas accumulations. These two sorts of anomalies sometimes coincidewith, and sometimes respectiely have some distance from, the projection of theoil and gas accumulation. This further demonstrates the effects of structural con-figuration on the anomalies.In addition,it is inferred that the location of oil andgas accumulation might be approached and determined on the basis of characte-ristics of mercury vapour aomalies and electrical anomalies.