Workover Cementing Techniques. (1) The Injectivity test

This injectivity test page is the start of a series of posts covering cementing techniques applicable during workover, including specific job requirements, fluid characteristics, and testing procedures. We will cover each of the following job categories: Remedial cementing, well abandonment, and fluids control/shut-off.

I am initiating this series of posts, (you can find links to the next two at the bottom of the page), with an essential step in remedial cementing and the squeeze process: the injectivity test. Over the years, I have seen operator and cementing contractors alike implementing either improper procedures or inconsistent data analysis.

Let’s start with the basis:
The injectivity test is performed before squeeze cementing or a gel injection, aiming to understand the well’s response (surface pressure, without exceeding the MASP – Max. Allowable Surface Pressure) at different pumping rates during the subsequent fluid treatment.

The most important factors to consider include: 

1. The fluids injected should be clean.
2. The wellbore should be circulated before injecting to prevent any plugging of the injection and flow path (perforations, leak in a casing, etc.). 
3. The injection should be conducted until pressure stabilizes for each step (5 to 10 min each). 
4. Increase rate while pumping pressure remains below target pressure or MASP.
5. Injection should be taken at rates that maintain pressure below the MASP and never exceeding the fracturing pressure. 
6. Operational procedures should be kept consistent between different wells to enable meaningful comparisons.
7. A perforation or leak wash treatment, e.g., small acid volume, may be applied to increase the injectivity.

Cheers,

L. Diaz

PS: Here are the links to the second and third articles in this series:

Workover Cementing Techniques 2: Squeeze Cementing

Workover Cementing Techniques 3: Plug Cementing