CBM

Case 1

 

Description
of Problem

 

New kudu pump 76K1200 was
installed in well on 11th May 2015 with pump setting depth at 928m
below all perforations and ran continuously till 9th June , 2015
despite increasing torque up to 115% limit.

While starting the pump at 100
RPM, the water level was 18m and the torque was 11.3%. On 8th June
2015, the water level had gone up to 412m, while torque had gone up to 54.2%,
The TDS of water was 2250 ppm while temperature of water on surface was found
to be 53 oC. No sand production was reported during entire period.

 

Inference
drawn out

 

The torque rise was seen
suddenly during start-up of the well it may be due to elastomer swelling or
stator choked with sand. As sand production was not reported so it can be
ruined out. The temperature of surface water was noted 53 o C so the
elastomer swelling is possible due to high temperature.

 

Recommendations:-

 

Ø  Use
under sized rotor.

Ø  Change
the stator.

 

Case 2

 

         
Description of Problem

 

 The 100 TP 1200 PCP was started after work
over on 1st June, 2015 with initial torque 32% and water flow rate
14 lpm. The variation in current and torque values started from the next day
and current variation from 25 to 31A, while torque variation from 36 to 54% due
to stick slip effect. Initially, sand production of around 1 kg/day was
observed in this well for two days, but after that the sand production ceased.
The pump ran continuously till 2nd October, 2015 with RPM ramped up
to 140, while water level staying around 700m. There were no major changes in
current and torque values.

On the well site visit on 2nd
October, 2015, no water flow was observed with torque variation between 12-45%
and current variation between 14 and 16A. The water level was recorded to be
679m. The PCP was stopped and again started on the next day, while also ramping
up the RPM till 300. The Current varied from 21 to 28A, while the torque varied
from 15-40%. Water production was not observed on the surface.

 

Inference
Drawn Out

 

The pump was running normally
from 1st June till 1st October. Since the torque
variation observed during the site visit on 2nd October was low and
no water production was reported, this could be due to tubing puncture in the
tubing string. Uncentralized rod string could be a root cause for the Tubing
Puncture. No water production was observed because as we produce water through
the tubing string, the water being produced falls back into the annulus due to
the tubing puncture.

 

Recommendations

 

Ø  Work
over job in order to change the tubing

Ø  Centralizers
could be inserted in the rod string in order to minimize tubing- sucker rod
contact.

 

 

 

Case 3

 

Description
of Problem

 

The well was completed with
new 70K900 KUDU pump on 26th April, 2015 with pump intake depth at
352m and run till 19th May, 2015. After that it was started on 10th
June, 2015 by self-flow.

Before routine start up on 16th
July, 2015 water level was 284m at 470 psi. When the PCP was started at 11:50
hours at 100 RPM without opening the tubing valve, the torque was found to be
9.8%, while current was 13.4A. the torque increase was not observed through the
tubing valve was not opened.

At 12:15 hours, the RPM was
ramped up to 150 with closed tubing valve and observed for 10 minutes but the
torque was only 10.8% at 13.6A. at 12:20 hours, the RPM was ramped up further
to 200 and observed for 10 minutes. But no increase in torque was observed- the
torque was 9.3% at current of 13.4A.

 

Interference
Drawn Out

 

From the above case it can be
interpreted as the torque observed was very less and there was a negligible
rise in the torque values on ramping up the RPM. This could be a reason of
sucker rod unscrewing or tubing unscrewing. The unscrewing of sucker rod or
tubing was the main reason for low torque values at high RPM.

 

Recommendations

Ø  Call
for a Work over job.

 

Conclusion:

Based on the study of
Challenge and prospect of CBM the following solutions can be drawn:

1.    
It is high time for the government to take CBM
sincerely and commissioning a complete system for its exploitation and
production in best possible way in India as other countries like USA, China,
and Australia.

2.    
Proper planning in this direction can lead to
fruitful results such as proper monitoring of CBM wells and well site
operations etc.

3.    
Technology plays an important role in the
development of CBM resources. Thus R&D must be a priority for the time being.