西南石油大学学报(自然科学版)

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Formation,Recognition and Analysis of Low-resistivity Annulus

Liao Dongliang1,2   

  1. 1. State Key Laboratory of Petroleum Resource and Prospecting,China University of Petroleum(Beijing),Changping,Beijing 102249,China
    2. Research Institute of Petroleum Engineering,SINOPEC,Chaoyang,Beijing 100101,China
  • Online:2014-02-01 Published:2014-02-01

Abstract:

The low-resistivity annulus is the strong evidence of available oil and gas,and the effective means of judgement of
oil and gas layer,especially the low resistivity oil and gas layer. Based on the flow equations of oil and water two phases,the
seepage driving velocity is derived during mud filtrate invaded formation,and the process of forming low-resistivity annulus
was analyzed. The high frequency induction log can get five resistivity curves at one time. From the reaction of the curves,we
can see there are three manifestations for low-resistivity annulus and they are R07 the lowest,R10 the lowest,R11 the lowest,
respectively. The paper analyzed the formation process of low-resistivity annulus and reservoir characteristics through the three
manifestations. Some examples of the three manifestations of low-resistivity annulus and the process result from high frequency
induction log were presented,the results shows that we can quickly tell the reservoir is oil layer,water layer or oil-water layer.

Key words: low-resistivity annulus, relativity permeability, flow equation, high frequency induction log, invasion depth