利用中子与密度测井勘探天然气

GAS EXPLORATION BY NEUTRON AND DENSITY LOGGING

石油部石油勘探开发科学研究院

数控测井系统具有数据采集与处理的功能。在测井数据采集或处理过程中,采用兼容横向比例尺记录中子与密度测井读数,根据它们的“-”交叉性质,可以直接勘探砂—泥岩剖面中的天然气。本文分析了中子与密度测井勘探南海崖13-1气田天然气的几个实例。在砂—泥岩剖面中,当岩石的中子测井读数小于密度测井读数时,两者出现“-”交叉,直观指示是气层。然而,当岩石的中子测井读数大于密度测井读数时,两者出现“+”交叉,直观指示是泥岩或水层。文中系统地论述了中子与密度测井勘探天然气的原理和方法。根据中子与密度测井读数交叉的性质而不是根据交叉的大小勘探天然气,这是该方法一个重要的新观点。文中给出的应用实例表明,利用中子与密度测井勘探南海崖13-1气田天然气,获得了令人满意的效果。

Numerical control logging system, has the functions of both the data acquisition and the data processing. In the procedure of data acquisition and data processing, the compatible lateral scale was adopted to record the readings of neutron and density logging and with their nature of"ne-gative difference", the gas reservoir of the sand-shale profile could be detected directly.In this paper, several examples of exploring the gas. field by neutron and density logging was presented. All of them were taken from the gas field of Yan-13-1, South China Sea. In circumstances of sand-shale profile, if the readings of neutron logging weer less than that of the density logging, then, the "negative difference" appeared, it indicates the presence of the gas visually; if the situation is on the contrary, i.e., if the difference is "positive", then, it's the indication of shale or water.The principle and technique of gas exploration by neutron and density logging were described systemaically in this paper. It is just the nature and not the value of the difference that means a great deal in gas exploration. This is something new in this article. Examples show that satisfactory results were achieved in gas exploration with neutron and density logging in the gas field of Yan 13-1 in South China Sea.