化探技术在隐蔽油气藏勘探中的应用

Application of the Geochemical Exploration Technique in Searching for Subtle Oil and Gas Reservoirs

正确认识化探技术在隐蔽油气藏勘探中的有效性和总结成功的隐蔽油气藏勘探实例,对我国现阶段隐蔽油气藏勘探具有十分重要的作用和意义。选择渤海湾盆地临南某断块隐蔽油气藏,利用化探精查技术对研究区化探样品酸解烃甲烷、重烃指标地球化学场特征进行描述和研究:该区存在稳定的酸解烃甲烷、重烃指标地球化学场,两酸解烃指标地球化学场亦具有良好的空间重现性,它们均以稳定的环状异常模式有效地指示了下伏断块隐蔽油气藏,该断块隐蔽油气藏的油气渗漏(油气微渗漏、夏口断层油气渗漏)与油气藏上方两酸解烃指标异常间存在着"因果"关系。鄂尔多斯盆地、准噶尔盆地等地区油气化探实例说明:化探技术在这些地区隐蔽油气藏勘探中取得良好应用效果的基础是化探方法选择、有效化探指标的选取和组合、化探指标综合异常信息提取、探区相关石油地质认识等多种因素的紧密结合。临南断块隐蔽油气藏油气化探的研究认识和鄂尔多斯盆地、准噶尔盆地等地区隐蔽油气藏的化探实例表明:化探技术可在隐蔽油气藏勘探中发挥重要作用。

To get a right knowledge of the effectiveness of the geochemical exploration technique in searching for subtle reservoirs and to summarize the successful exploration cases of such reservoir types are essential for the exploration of subtle oil and gas reservoirs at present. A subtle fault block oil reservoir in the Linnan area, Bohai Bay basin was chosen as an example, and the characteristics of the geochemical fields of both the acid-extraction methane and the heavier hydrocarbons were studied and characterized in detail by using the intensive geochemical exploration technique. The results show that both the acid extraction methane and the heavier hydrocarbons have stable geochemical field in the study area; and the geochemical fields of the two kinds of acid-extraction hydrocarbon indicators coincide very well, both effectively indicating the underground subtle fault block oil reservoir with stable ring-like anomaly patterns. The results also show that there are causal relationship between the hydrocarbon seepage （both the microseepage and the macroseepage along Xiakou fault） from this subtle oil reservoir and the anomaly of the two acid-extraction hydrocarbon indicators. The other exploration cases from Odors basin and Junggar basin demonstrate that the fundamental base for the geochemical technique to be used effectively in exploring the subtle fault block oil reservoir is comprehensively combining various factors together, including choice of the geochemical methods, selection and combination of the effective geochemical indicators, extraction of the integrated anomaly information, and recognition of the related petroleum geological conditions. The study results of Linnan area and the geochemical exploration cases of Ordos basin and Junggar basin indicate that the geochemical exploration technique can play important roles in the exploration for subtle oil reservoirs.