GR/CCL Correlation

Maximizing Well / Reservoir Integrity — A Practical Guide for Understanding GR/CCL Correlation and the Cement Evaluation Logs

Introduction

Oil & gas well operations involve lots of complex processes, and one of the most vital processes is well casing integrity and cement quality evaluation. Advanced techniques such as Gamma Ray/Caliper (GR/CCL) correlation, Cement Evaluation Logs and Baseline Hydraulic Retention Time (HRT) Logs are used to attain this. This article covers in-depth how to run these important well integrity testing and evaluation steps and the Standard Operating Procedure (SOP) leveraged to do so.

GR/CCL Correlation and Cement Evaluation Logs

1. Engineer's Presence

It starts with the engineer visiting the site for shallow correlation and a full analysis of logs. Their knowledge guarantees accurate interpretation of data, consequently improving the precision of the logging operations.

2. Lubricator Setup

The next important step is to set up the lubricator. This involves:

✔R/U lubricator with GR/CCL log (and cement evaluation log or HRT log if required)

✔Removing the lubricator from the BOP to ensure the safety and stability of operations.

3. Valve Top and Manifold Inspection

Here are the steps undertaken in preparation for logging:

✔The Tubing Kill Valve (TKV) and Christmas Tree Valve (CV) valves will be opened up as well as the two wing valves

✔Opening the choke manifold valves for an environment to operate in.

4. Tree Flush Procedure

Tree flush: A proper tree flush is vital for removing debris and obtaining accurate readings:

✔A 70% water and 30% glycol mixture flushes contaminants across the tree.

✔Closing the choke manifold valves keeps the clean and controlled.

5. Lubricator Priming

The lubricator is primed by to work efficiently:

✔Put a 70% water — 30% glycol mix in it, removing air and ensuring it operates smoothly.

6. Pressure Testing

Pressure testing is a vital safety check to confirm the integrity of equipment:

✔Water/Glycol mixture transmitted to the lubricator at 7500 PSI.

✔Test the 10-minute pressure — As we know, all engineering products need to be tested for its reliability under operational conditions.

7. Pressure Bleeding

So to ensure a safe workplace, you have to:

✔Potentially hazardous release pressures are gradually brought down in the tree and lubricator to align with the Shut-In Wellhead Pressure (SIWHP).

8. Leak Monitoring

To prevent hazards:

✔Complete enough to test personnel in the conservator to ensure there are no gas leaks from the lubricator.

9. Safety Measures

To improve safety when in operation:

✔A representative of the utility service must unlock the lockout cap before the HMV can be operated.

10. Logging Operations

The heart of this process is logging:

✔RIH in the hole with the appropriate logging tools.

✔An optional dummy run (fired perforating gun) with GR/CCL log to improve efficiency and data gathering.

11. Positioning and Confirmation of the Tool

They possess the following features to ensure accurate data acquisition:

✔POOH, Pulling our of the hole until the tool is inside the lubricator.

✔Before continuing, close the CV and affirm available tools in the retained position.

12. Finalizing Operations

✔To safely terminate the process:

✔Fusing CV, opening, closing HMV.

✔Dumping any excess pressure via choke manifold or Back-Down (BD) line.

✔Giving the tree a good flush with water.

13. Wireline Operations Completion

✔To close the operation properly:

✔It includes: -- Closing the Choke Valve (CV) and Rig down (RD) the wireline operations, marking the completion of logging activities.

14. Well Securing

The last step is to see that all is well secured:

✔Confirming all safety protocols have been followed.

✔Integrity testing the well for subsequent operations.

✔Limitations of Cement Evaluation Logs vs. GR/CCL Correlation

✔The correlation of GR/CCL and cement evaluation logs.

Well Integrity Management: Casing and cement integrity maintenance should ensure the condition of all casing elements is optimal to avoid well failures in subsequent working phases.

Improving Safety: Running on correlation accurately helps in not having mistuned jobs, which can result in well integrity problems.

Production Optimization: Cement evaluation logs are utilized to assess cement placement quality, which plays a key role in well performance and longevity.

Reducing Risks: The early identification of anomalies can help avoid expensive remedial work and boost general well efficiency.

Conclusion

The SOP for GR/CCL correlation and cement evaluation logs must be strictly adhered to for optimizing well integrity in oil and gas operations. Every phase within the process is carefully crafted to minimize risks, improve data accuracy, and maintain industry standards. Maintaining the integrity of the well casing and adherence to cement quality ensures the safety, efficiency, and cost-effectiveness of the operations; thereby allowing the long-term retention of oil and gas reservoirs.