油气藏自然电位勘探原理及在开发中的应用

自然电位勘探是油气藏地球物理勘探的重要内容之一，研究的重要内容是自然极化机理。简要介绍油气藏氧化还原电位学说和自然电位非极化成因的长分子烃裂解学说。提出油气-水溶液和岩石-油气离子极化机理，产生极化电动势的条件前者主要是油气扩散运移、水溶液向下沉降以及还原梯度变化，后者主要是油气的扩散运移，建立了极化概念模型。油气藏存在极化电动势是共性，可以将整个油气藏、扩散带和扩散流动带作为场源，其极化电动势可用极化偶极模型描述。导出了基于极化偶极和电流观点的位场解析表达式。室内和野外模型实验以及不同模型的正演计算，证明了极化理论的正确性。在实验基础上，成功地将自然电位法用于在油田开发领域寻找高效区块，进行油田开发扩边。根据东北地区某油气藏地表自然电位异常大小、宽度、边部梯度等指标，结合其它地质资料，共预测65口开发井的开发效果，预测成功率为85％。图7参5（王君恒摘）

Self-potential detection principle of oil/gas reservoir and its application to field development

Self-potential is one of important criteria in geochemical exploration.The important content of self-potential study is the mechanism of natural polarization. This paper introduces theories of oxidation-reduction potential and non-polarized cracking of long chain hydrocarbons.Mechanisms for ion polarization of oil/gas-aqueous solution and that of rock-oil/gas are suggested. Conditions responsible for polarized potential production are diffusion-migration of oil and gas,downward descending of aqueous solution, as well as the change of reduction potential gradient in the former; and diffusior-migration of oil and gas in the later. A conceptual model polarization is established. The presence of polarized potential is a general property of the existence of an oil/gas reservoir.The whole oil/gas reservoir together with its diffusion-flowing belt can be taken as the source of the potential field, and the polarized potential can be described by a model of polarized dipole. An analytical expression of potential field is derived based on a viewpoint of polarized dipole and electrical current. Calculations by using in-house model, field model experiment, and various models prove the correctnes of this theory. On the basis of laboratory experiment, self-potential technique is applied effectively to locate highly effective blocks and extension of oil/gas field. With the criteria of an oil/gas reservoir in Northeastern China such as size, wide, boarder gradient of its surface self-potential etc. and combined with other factors, the development results of 65 develoment wells are predicted with success ratio reaching 85%.