不同勘查阶段油气化探异常的地质意义

油气化探工作要遵循先区域后局部、调查比例尺由小到大的原则，在不同的勘查阶段圈定不同级次的异常，逐渐逼近油气藏的空间范围。不同阶段测量精度决定了所发现化探异常的油气地质意义：概查阶段应在盆地背景上圈定区域异常，查明盆地的含油气远景；普查阶段应在区域背景上圈定区带异常，查明油气富集的有利区带；详查阶段应在地区背景上圈定局部异常，查明圈闭的含油气性；精查阶段应在局部背景上圈定矿置异常，查明油气藏的存在与位置。各级次化探异常之间具有依次控制的关系，前两类化探异常属于宏观异常，与油气藏的关系是不甚确切的，后两类异常则反映了油气藏的具体特征。应用不同级次异常的概念，在我国海域和陆地的诸多盆地中进行的化探工作，为油气勘探、开发提供了信息和依据，取得了良好的地质效果。图４表６参４（梁大新摘）

Geologic significance of oil and gas geochemical prospecting anomalies in different phases of exploration.

The geochemical prospecting (GP) for oil and gas should follow the principle of regional surveying before local surveying and of surveying scale from small to big, as well as at different surveying stages delimiting different classes of anomalies, by so doing people can gradually approach the outline of oil and gas fields. Surveying precision determines petroleum geologic significance of GP's anomalies. Reconnaissance: delimiting regional anomalies on the background of a basin, indicating petroleum prospect of the basin; general survey: delimiting zonal anomalies on the regional background, indicating favorable zones for oil and gas accumulation; detail survey: delimiting local anomalies on the zonal background, indicating petroleum potential of a trap; intensive survey: delimiti China. ng mineral anomalies on the local background, indicating the existence of a field and its location. The foretwo genus anomalies belong to macro anomalies, they have not exact relation with oil and gas field, the steptwo genus anomalies indicate the feature of oil and gas fields, they have the relationship with each other by controlling in proper order. Applying concept of different class anomalies, GP has provided information and basis for oil and gas exploration and development, and gained batter geologic effects in many onshore and offshore basins of