Permanent Downhole Monitoring

To summarize the current state of the art in Permanent Downhole Monitoring (PDM) an outlook and recommendation for future development and research for both the service industry as well as academia is provided. We further propose suggestions and decision aids for Principal Investigators (PI) and scientists referring their selection criteria for an array system on the basis of reliability, sensitivity, risk of failure and investment cost.  

Types of Installation

The systems suitable for PDM can be categorized in two types of installations: 

  1. Outside the casing, facing the rock formation and permanently cemented in place, and
  2. Inside casing or open hole by means of wireline or pipe deployed with a retrieval option. 

Common to both types is the requirement for a long downhole life expectancy in the form of a system reliability of minimum 5 years mean-time between failure (MTBF) combined with a measurement repeatability over comparable periods.