Well Integrity Technical Section

This is a gas well on land.
The well schematic is attached. The xtree has the basic Primary/secondary master, wing, flow and swab valves.

1.    The regulations require that the production casing be cemented to surface.
This was unusual for me since annulus monitoring is no longer possible. Trying to cement 7" in 9 5/8" for 1320m in a single stage is a difficult task much less trying to ensure good cement integrity. A number of wells are showing sustained B annulus pressures.
Does anyone have any thoughts as to why gov regulations would require this?

2. These wells require dual barriers.

Gov Regulations:
The well has been constructed with both primary and secondary mechanical well barriers. The primary mechanical barrier is the barrier that is exposed to the flow stream. The primary mechanical barrier shall be able to withstand full operating pressure as demonstrated by the pressure testing.
The secondary mechanical barrier is not exposed to the flow stream under normal operations. The secondary mechanical barrier shall be able to withstand full operating pressure as demonstrated by the pressure testing required.

The regulation is correct, however, if interpreted correctly this means that a TRSSV is NOT required. Instead the Primary and secondary master valve is sufficient to fulfil the requirement of a dual barrier system.

Does anyone have any thoughts as to why gov regulations would not recognize a single point failure at the Xtree (both valves) as a weakness to the well barriers? (example a truck running into the Xtree)

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------

Hi Basker,

Let me start from the end: the regulation doesn't seem to require "independent" barriers, which would rule out common elements (though this is only a necessary but not sufficient condition i.e., it's a good start). But it does require that "is not exposed to the flow stream under normal operations". This would exclude all of your master valves from being part of the secondary barrier. Obviously, this is not advisable. As it is an abomination to split the two master valves, which - together - only make a more reliable single barrier element. I know it was a joke, but you cracked my moral certainty.

I guess that since the regulations cannot be followed to the letter, you grab a recognized standard (NORSOK or OEUK) and do the barriers design as tradition requires. By the way, they may have been inspired by ISO 16530 5.7.3.3 so, obviously, you need to be compliant with that standard before deep diving into technical documents.

Now to the question about psychology and motivation of regulators (not necessarily my speciality): there are many places requiring that you cement wells to surface. The purpose is to minimize vertical movement of brine or oil, which would lead to aquifer pollution away from a possible tubular leak. This requirement doesn't apply to a gas producing well, though you may want to satisfy it nonetheless in case you convert the well to water injection. Funny that your surface and intermediate casings are not cemented to surface, because those are the ones involved in pollution cases.

As a separate consideration, in general it is advisable to reduce the isolatable inventory of gas. Shallower ToC means less gas that can accumulate in the annulus and be released. This may also play a role in the requirement.

On the negative side, big cement leaks will hit your B annulus - at least initially - but microannuli may hop to the outside and you may have a real leak instead of a primary barrier failure. In your case, though, the 8½" open hole looks really short, so you will end up placing cement in the double string section anyway. Might as well bring it up as far as you can.

Best regards,

------------------------------
Matteo Loizzo
Well integrity consultant
matteo.loizzo@mac.com
Berlin, Germany
------------------------------

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten
------------------------------

Sadly, I was quite shocked to find that these regulations were actually USA regulations for land wells.

Reasons I do not like cementing such a long production casing to surface

• Inability to monitor what is going on in the annulus. Its  a black hole
• Inability to sidetrack in the future ......easily
• Inability to rectify any sustained pressure....easily. (as we have them now)
• Trying to cement 7000ft of 0.75" (centered) annulus with a perfect cement bond is a real challenge.

As for the lack of a TRSSV on a self erupting hydrocarbon well as a basic safety requirement, I cant really explain that.....

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------

Original Message:
Sent: 06-18-2023 07:40 AM
From: Robert Peters
Subject: A question related to gas well design and well integrity

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten
------------------------------

To TRSSV or not: DHSV's are critical for offshore operations, where there is a long track record of losing wellheads due to platform fire, storms, or ships.  With the loss of a wellhead, a DHSV is invaluable.  However, there is also a long track record of DHSV failures, requiring workovers.  The historical probability of having a blowout during a workover is orders of magnitude higher than having a blowout during production.  You need to weigh the full risk profile to choose to use a DHSV or not.  On land wells that analysis has typically concluded that not using DHSV's are the lower risk option.  There are of course exceptions, such as close to environmentally sensitive areas.  You concern about a truck taking out the Xmas tree can be managed by installing physical barriers around the well: this is a cheaper and more effective solution than a DHSV.

I am not sure what regulatory body you are working under.  Although I have been told that cement to surface is required in the USA, I have always found that not to be the case when reading the regulations carefully.  For the surface casing, cement to surface is required. 

I would recommend some careful reading of the regulations with regards to required TOC for the production casing.

Original Message:
Sent: 06-19-2023 06:09 PM
From: Basker Murugappan
Subject: A question related to gas well design and well integrity

Sadly, I was quite shocked to find that these regulations were actually USA regulations for land wells.

Reasons I do not like cementing such a long production casing to surface

• Inability to monitor what is going on in the annulus. Its  a black hole
• Inability to sidetrack in the future ......easily
• Inability to rectify any sustained pressure....easily. (as we have them now)
• Trying to cement 7000ft of 0.75" (centered) annulus with a perfect cement bond is a real challenge.

As for the lack of a TRSSV on a self erupting hydrocarbon well as a basic safety requirement, I cant really explain that.....

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------


Original Message:
Sent: 06-18-2023 07:40 AM
From: Robert Peters
Subject: A question related to gas well design and well integrity

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten

have you considered cementing 7" in 2-stages, with ECP.?  or setting liner then tieback to surface?  would add cost and time, and a bit of additional risk, but would also take some of the mystery out of what's happening downhole. eqp't such as expandable liner-hangers, metal ECP's, newer non-inflate compression-set ECP's, etc, might all be considerations.

------------------------------
Scott Myers
------------------------------

Original Message:
Sent: 06-19-2023 06:09 PM
From: Basker Murugappan
Subject: A question related to gas well design and well integrity

Sadly, I was quite shocked to find that these regulations were actually USA regulations for land wells.

Reasons I do not like cementing such a long production casing to surface

• Inability to monitor what is going on in the annulus. Its  a black hole
• Inability to sidetrack in the future ......easily
• Inability to rectify any sustained pressure....easily. (as we have them now)
• Trying to cement 7000ft of 0.75" (centered) annulus with a perfect cement bond is a real challenge.

As for the lack of a TRSSV on a self erupting hydrocarbon well as a basic safety requirement, I cant really explain that.....

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------


Original Message:
Sent: 06-18-2023 07:40 AM
From: Robert Peters
Subject: A question related to gas well design and well integrity

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten

Hello Basker

Installation of TR/WR SCSSV's in land wells is the exception rather than the rule on a percentage basis given that there are probably over 100,000's wells globally that will flow naturally to surface - there are several 10,000's in N America alone.  So, I think it goes back to what are the risks that need / are being mitigated? What is the consequence of failure? Several wells have tertiary physical barriers to prevent such things as vehicles "knocking over" XTrees, breaking flowlines and so on.  Does introducing distributed networks of hydraulic control lines introduce other risks?

I agree with Hans-Jacob that on first reading some regulations appear to specify that a production casing must be fully cemented from the reservoir to the well head.  You may want to discuss this with the local regulator's inspector to see how the particular regulation is applied in practice.  Some regulators do require the surface and first intermediate casing to be fully cemented to surface as there are particular known issues that need to be addressed; aquifers, corrosive flow, shallow gas, spalling/sloughing formation.....

I guess as a final resort, you could consider changing the casing and cementing design to allow for a larger annulus to help achieve the primary cement placement and performance that you wish.

Alex.

------------------------------
Regards
Alex
------------------------------

Original Message:
Sent: 06-20-2023 02:25 PM
From: G Myers
Subject: A question related to gas well design and well integrity

have you considered cementing 7" in 2-stages, with ECP.?  or setting liner then tieback to surface?  would add cost and time, and a bit of additional risk, but would also take some of the mystery out of what's happening downhole. eqp't such as expandable liner-hangers, metal ECP's, newer non-inflate compression-set ECP's, etc, might all be considerations.

------------------------------
Scott Myers
------------------------------


Original Message:
Sent: 06-19-2023 06:09 PM
From: Basker Murugappan
Subject: A question related to gas well design and well integrity

Sadly, I was quite shocked to find that these regulations were actually USA regulations for land wells.

Reasons I do not like cementing such a long production casing to surface

• Inability to monitor what is going on in the annulus. Its  a black hole
• Inability to sidetrack in the future ......easily
• Inability to rectify any sustained pressure....easily. (as we have them now)
• Trying to cement 7000ft of 0.75" (centered) annulus with a perfect cement bond is a real challenge.

As for the lack of a TRSSV on a self erupting hydrocarbon well as a basic safety requirement, I cant really explain that.....

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change


Original Message:
Sent: 06-18-2023 07:40 AM
From: Robert Peters
Subject: A question related to gas well design and well integrity

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten

Thanks for all the feedback, its much appreciated.

1. For the cementing production casing to surface, we have yet to get an understanding from the regulators as to why they require this.
   It would appear this was someone "good idea", not quite understanding the ramification of what they were asking.
   
   
2. As for the TRSSV, these are gas wells.
   Being self eruptive, any accident to the tree will cause an uncontrolled HC exposure.
   The risk to reputation of a fire or blowout is simply not worth the risk for a TRSSV unit that is less than 30K.
   Intrestingly, the incident has already occured where an eco terrorist stole a truck and ran thru the physical barrier and damaged the tree. This caused a HC breach at surface and the associated well control measures were taken. In this day an age, when O&G is under pressure to transition to green energy, eco terrorism has become a reality, regardless the risk with a truck or with a drone, the risk is clearly a serious matter.
   
   I found the most interesting reason given not to run TRSSV's on land has been that it fails quite often.
   This is simply a matter of experience installing and operating TRSSV's. We have used them extensively offshore and in Deepwater and learnt how to maintain and operate then effectively because we were forced to do it. With time, the reliability of TRSSV operations has dramatically improved. Learning this on a land operation. is not much different.
   After all, one of my early mentors in completion design said " the well does not know if its offshore or in deepwater or on land, only we do"

Thanks again for your comments and recommendations.

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change
------------------------------

Original Message:
Sent: 06-21-2023 01:41 PM
From: Alexander Crabtree
Subject: A question related to gas well design and well integrity

Hello Basker

Installation of TR/WR SCSSV's in land wells is the exception rather than the rule on a percentage basis given that there are probably over 100,000's wells globally that will flow naturally to surface - there are several 10,000's in N America alone.  So, I think it goes back to what are the risks that need / are being mitigated? What is the consequence of failure? Several wells have tertiary physical barriers to prevent such things as vehicles "knocking over" XTrees, breaking flowlines and so on.  Does introducing distributed networks of hydraulic control lines introduce other risks?

I agree with Hans-Jacob that on first reading some regulations appear to specify that a production casing must be fully cemented from the reservoir to the well head.  You may want to discuss this with the local regulator's inspector to see how the particular regulation is applied in practice.  Some regulators do require the surface and first intermediate casing to be fully cemented to surface as there are particular known issues that need to be addressed; aquifers, corrosive flow, shallow gas, spalling/sloughing formation.....

I guess as a final resort, you could consider changing the casing and cementing design to allow for a larger annulus to help achieve the primary cement placement and performance that you wish.

Alex.

------------------------------
Regards
Alex
------------------------------


Original Message:
Sent: 06-20-2023 02:25 PM
From: G Myers
Subject: A question related to gas well design and well integrity

have you considered cementing 7" in 2-stages, with ECP.?  or setting liner then tieback to surface?  would add cost and time, and a bit of additional risk, but would also take some of the mystery out of what's happening downhole. eqp't such as expandable liner-hangers, metal ECP's, newer non-inflate compression-set ECP's, etc, might all be considerations.

------------------------------
Scott Myers


Original Message:
Sent: 06-19-2023 06:09 PM
From: Basker Murugappan
Subject: A question related to gas well design and well integrity

Sadly, I was quite shocked to find that these regulations were actually USA regulations for land wells.

Reasons I do not like cementing such a long production casing to surface

• Inability to monitor what is going on in the annulus. Its  a black hole
• Inability to sidetrack in the future ......easily
• Inability to rectify any sustained pressure....easily. (as we have them now)
• Trying to cement 7000ft of 0.75" (centered) annulus with a perfect cement bond is a real challenge.

As for the lack of a TRSSV on a self erupting hydrocarbon well as a basic safety requirement, I cant really explain that.....

------------------------------
Basker Murugappan
Principal Production Technologist
Villalbilla, Spain
+34 644485970

Three basic rules:
1) Change is inevitable.
2) Everybody resists change.
3) You cant stop change


Original Message:
Sent: 06-18-2023 07:40 AM
From: Robert Peters
Subject: A question related to gas well design and well integrity

Hi Basker,

You should not consider Upper and Lower Master Valves as separate barriers - for reasons already mentioned. SSSV's are difficult to get truly leak-tight, but most regulators I am familiar with accept API acceptance standards as sufficient to class them as a barrier if they pass a regular inflow test.

Why is the 7" run as a casing, and not as a liner in your well design? Seems a waste of steel? Unless the burst of the 9.5/8" is insufficient, but at that depth a P110 should be able to deal with most 'normal' circumstances?

Have you confirmed this need to cement production casing to surface with your Regulator? It seems to introduce more risk rather than solve anything. With a regular cement weight at such shallow depth I would imagine a real risk of fracking the formation at the shoe of the 7" with a full column of cement sitting on it? Usually the requirement to cement to surface applies to the surface casing only, protecting groundwater resources. Sound annulus management then can confirm integrity of the inner strings.

Rob

------------------------------
Robert Peters
Voorschoten