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Multistage Stimulation in 2 different sizes
01 February 2019
Dear community,

I am faced with a well design where the reservoir has two different layers. Kimmeridgian layer  (which is above) with a  formation pressure  much higher than the Callovian layer below.

Meaning, production casing (7") will be run up to Kimmeridgian layer and off-bottom cemented. For Callovian layer, would be run 4.5" uncemented production liner. 2 zones will be in casing part and another 2 zones will be in liner part.

Upper completion will be consisted by tieback stinger, production packer, sliding sleeve, chemical injection mandrel & safety valve.

All this would be run on 3.5" 9.2# tubing. I want open hole sliding (frac) sleeves to open/close by coiled tubing and install 2 each in liner & 2 each in casing. Isolate each zone with open hole packers.

 I want to open each zone and perform acid/prop fracturing and produce each zone one by one.

I need your advise if you think it is feasible.

Thanks in advance,
 
Daniyar
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7 answer(s)
Dan
Workover Engineer
SPREAD Associates
Total Posts: 9
Join Date: 01/08/18

Dear Daniyar,

Here are my concerns:

1.    Setting a deep-set packer (or a liner hanger) inside of an uncemented casing (in this scenario it is 7`` liner)

2.    Expose 7`` stage frac sleeve to cement, when off bottom 7`` liner cementing job is performed; what shall I recommend is to run a risk assessment to identify the likelihood of ending up with simply perforate the stage frac sleeve to have communication with the upper layer, once the 7`` liner is cemented. Depending on the risk assessment findings to evaluate if not better to cement the 7`` liner and then perforate the liner

3.    Ask reservoir engineer accept on your new tubing size you would like to use (from possible future workover jobs perspective, a bigger completion size is always preferred)

Hope this will help you in taking the safest and fit for purpose solution to complete your well.

Dan  

udaniyar
Job Delivery Lead
Schlumberger
Total Posts: 4
Join Date: 16/07/16
Dear Askhat,

Thank you for your time wasted for drawing. You made the correct sketch. And you raised good questions.  

1) Shifting tool that I want use to open & close 4.5” frac sleeves has 2.3” OD in RIH position. But for 7” frac sleeves I have 3.45” OD. The first reason of this ticket was on shifting tool OD, if anyone has smaller size to operate big size, such as 7” sleeves.

2) Yes, we have a damage, wear, unintentional opening risks of 7” sleeves while drilling 6” OH. The second reason of this ticket is, if anyone from community had any experience of similar cases and if can share with me. My opinion on this, in case unintentional opening we always can run shifting tool and close (not ideal case but will work). In case of wear & tear casing patch would be proposed to isolate if you want to abandon the zone.

3) We have CT Packer which might be set above each sleeve and frac to upper port.

4) If you are meaning sleeve in open or in closed position, we can check it with shifting tool, in case if we won’t understand which port is not holding we can run CT Packer, set above each sleeve and pressure test upper one.

Analyzing all mentioned points, I am thinking to use 4.5” tubing instead 3.5”. This will allow to pass with 3.45” OD shifting tool. But Safety Valve OD with 4.5” connection will not pass thru 7” casing, that is why 7” part will be hanged as liner in the previous casing. I`ve attached the well schematic for your review. Please let me know your thought.

Thanks,

Daniyar

Documents uploaded by user:
Proposed Well Schematic.jpg
udaniyar
Job Delivery Lead
Schlumberger
Total Posts: 4
Join Date: 16/07/16
Dear Dan,
Sorry for confusing with the tieback stinger. In this scenario upper completion will not be stabbed in to the lower completion.
Regards,
Daniyar


Dan
Workover Engineer
SPREAD Associates
Total Posts: 9
Join Date: 01/08/18

Dear Daniyar,

As Askhat did, I also made a well completion schematic to figure up how you will intend to connect the reservoir to surface production facility. I think it will be more beneficial if you can share a well completion schematic to be used as a starting point for our discussions. In Askhat schematic I see no tieback stinger you are mentioning in upper completion section. To go further I will say that, I have not heard that a deep-set packer to be set inside of an uncemented casing, so this is one of my concerns (the 4 ½’’ liner hanger which incorporates the tieback stinger you are suggesting for upper completion). As for CT tools availability, Askhat is mentioning, they are not a concern and also well barrier envelope integrity can be stage by stage checked, lower completion set and upper completion set. The fit for purpose design of liner shoe and running the frac sleeves in closed position will allow this check. The tricky thing I am not figure up in your suggested well completion is how the two upper sections of the reservoir will be connected to surface.

Askhat
Well Test Engineer
ALMEX PLUS
Total Posts: 22
Join Date: 24/12/14
Dear Daniyar,
I've made some sketch to understand the well design you described, please see the attachement.
For me there are several questions arise:
1) Is the CT tools available for 7" and 4-1/2" to be run thru 3-1/2" tubing?
2) Any concerns for 7" sliding sleeves during drilling and liner running operation (damage, wear, unintentional opening)?
3) Contigency plans for sliding sleeves mulfunctioning;
4) How to check well integrity before and after each zone?

Regards, 
Askhat.

Documents uploaded by user:
Well_noname1.jpg
udaniyar
Job Delivery Lead
Schlumberger
Total Posts: 4
Join Date: 16/07/16
Dear Dan, Yes you are correct. 4.5" liner hanger will be set in uncemented part of previous 7" casing. Do you see any issue on this? Response for first question ; 7" packer will be set above upper zones. Regards, Daniyar
Dan
Workover Engineer
SPREAD Associates
Total Posts: 9
Join Date: 01/08/18
Dear Daniyar,

My question to you is how the well will be stimulated, once it will be completed? (how is connected the reservoir to production string for the two upper zones?)

Also the 4 1/2 liner hanger will be set on an uncemented casing, in my understanding, isn`t it?.

Those two aspects are coming into my mind now as potential issues with the suggested completion.

Dan

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