Motivation

The idea of SBT is to 

Objectives

Assess formation pressure in perforated formation units. 

Data Acquisition Procedure

1. Design survey
   
   
   1. Assess the duration of required shut-in period
      
      
   2. Assess the expected static fluid level based on the minimal expected formation pressure around the well
      
      
   3. Assess additional depth extension in order to capture the pressure gradient  in static fluid column
      
      
2. Shut-down the well for a pre-calculated period of time
   
   
3. Pull down the memory gauge at pre-calculated depth 
   
   
4. Retrieve the tool at surface and download the data

Data Interpretation

Assumptions and Limitations

The survey assumes that

• the achieved shut-in conditions are representative of the formation pressure
  
  
• the fluid column across the surveyed interval stays the same all the way down to the formation datum
  
  

The survey is applicable for wells with one perforated unit with no integrity issues (behind casing communications, active leaks or leaky bottom-hole)

The survey is applicable for wells with multiple perforations providing that all perforated units have the same formation pressure so that well doe snot develop a cross-flow between perfoations during the survey.

In most practical cases the above conditions are not met and SGS maybe highly misleading.