Abstract
The productive life of a well can be affected by deterioration of the well integrity which can be due to casing/tubing corrosion, casing damage during drilling/ work over, packer failure, plug failures, cement integrity issues etc.
Remedial measures can be executed if the nature of problem is diagnosed. One can receive early warning of a potential problem and obtain data for determining a specific restoration program by running well integrity diagnostic tools. There are various well integrity tools available to cater evaluation needs at present times with different working principles and targeting different well integrity problems such as casing/tubing and cement integrity. However, in challenging situation and complex environments, the tools may not provide complete diagnostics.
Production logging can be an effective tool in such scenarios by mapping the flow behaviour in the wellbore and can provide a better idea of the wellbore problems.
The well "A" is a development well which was drilled (max angle~ 27º) and completed in the interval X345-X349m and X362-X368m to exploit gas from the reservoir ABC. During initial testing it produced @ 1, 67,000 m3/d with FTHP of 2348psi. Later after acid job rate increased to 2,20,000 m3/d but later well had frequent water loading problem and required frequent activation / stimulation. The well has good reservoir zones as identified on the OH logs, hence, to diagnose the reason for water production, PLT was planned in the well in 2015. The well was producing 1,00,000 m3/d of gas at an FTHP of 1181psi during that time. Annulus pressure build-up was also observed in the well suggesting integrity issue with packer/tubing.
During the PL run, it was observed that the packer has fallen and settled across one the perforation and the flow was observed to be ongoing from inside as well as outside the packer element making the flow interpretation tricky.
A proper interpretation was carried out taking into consideration all available data and water entry point was confirmed. Based on the results, a well intervention was carried out and after the job, well started producing 1,50,000 m3/d of gas with 0% water cut whereas before it was producing 1,00,000 m3/d of gas with 1900 BPD of water. Thus, the intervention resulted in production enhancement by 50% and reduction in water cut by 100%.
This paper highlights the proper analysis of the recorded data for diagnosis of the flow condition in an adverse and complex scenario and finding out the water entry point for a proper remediation of the well integrity and production issue.
