plug & abandonment
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Plug & Abandonment challenge
CHALLENGE: Faster and cheaper casing removal
How can we remove the whole of or intervals of casing strings more efficiently?
Q:
CHALLENGE: Faster and cheaper casing removal
• P&A and especially slot recovery operations require removal of old casings. The casing string can be troublesome to pull: The string may be stuck, the settling of particles in the annulus mud can cling to the casing strings. Time-consuming multiple cut and pull operations are then necessary to remove the casings.
• How can we reduce the number of cuts necessary to pull a casing string (for example for stuck casing)? Can we develop multi purpose tools (cut & pull; release, cut & pull)? How can we handle the pulled casing more efficiently on deck top side? Does there exist – or can we develop – logging tools for identifying where the casing string is stuck?
How can we remove the whole of or intervals of casing strings more efficiently?
CHALLENGE: Alternative methods for creating an annulus barrier
Can the sealing of a well at the end of its production be performed in a different way and still prevent gas or fluid from reaching the surface?
Q:
CHALLENGE: Alternative methods for creating an annulus barrier
• Currently, an oil well is plugged at the end of its production by placing barriers in the wellbore to prevent gas or fluid from leaking to the surface. This is done by removing the tubular in an interval, followed by placing a cement plug in the wellbore.
• Alternatively, an interval may be identified, where the outside of the tubular is sealed off (by cement or expanding formations), and a cement plug is placed on the inside without removing the casing.
Can the sealing of a well at the end of its production be performed in a different way and still prevent gas or fluid from reaching the surface?
CHALLENGE:
Alternative materials for annulus barriers
Does there exist, or is it possible to develop an alternative material which is easily placed, that will seal for eternity and allows for shorter plug length?
Q:
Photo © NCA
CHALLENGE:
Alternative materials for annulus barriers• Today, cement is the material used to create an annular barrier in a P&A
operation. However, several challenges are related to this:
− The placement of the product/displacement of fluid in place. How do we ensure the whole annular cross-section is filled?
− Long term sealing capacity. What should be the required mechanical properties?
− Shrinkage. How do we avoid “voids”?
− Length requirement for barrier element. What minimum plug length is needed to ensure sealing?
Does there exist, or is it possible to develop an alternative material which is easily placed, that will seal for eternity and allows for shorter plug length?
CHALLENGE:
P&A without cutting and pulling the tubing and casing
Q: Is there a way we can safely leave the tubular downhole and still be able to seal off the well for eternity?
CHALLENGE:
P&A without cutting and pulling the tubing and casing
• Permanent P&A is today done by cutting and pulling the tubing and casing in order to set a cross-sectional barrier plug. There are multiple annuli that have to be sealed.
• But are there options to removing steel tubular without cutting and pulling? How do we verify the cross-sectional barriers we leave behind?
Is there a way we can safely leave the tubular downhole and still be able to seal off the well for eternity?
CHALLENGE:
P&A of subsea wells without a rig
How can we plug and abandon subsea wells without the use of a rig?Q:
CHALLENGE:
P&A of subsea wells without a rig• Historically, P&A has been performed using a rig. The tubing is normally pulled,
and part of the casing is either cut and pulled or section milled in order to set the permanent barrier plug. Performing permanent P&A of subsea wells from a rig can be very expensive and time consuming.
• By using a vessel (ship) instead of a rig for permanent P&A we are currently not able to remove the casing and tubing. The challenge is to set and verify the permanent barriers in the whole cross section without the use of a rig.
How can we plug and abandon subsea wells without the use of a rig?
CHALLENGE:
Logging through multiple casings
Photo © Archer
How can we log through several layers of steel with the same or higher level of interpretation quality as today?
Q:
CHALLENGE:
Logging through multiple casings• Ahead of a P&A and slot recovery operation it is essential to validate the
condition of the sealing material outside the tubing. We need to know the height and quality of the seal, including the degree of bonding, presence of pockets, cracks and channels, distinguish between the barrier material (cement) and the formation or settled barite from the mud, the presence of gas in the annulies, etc. A lack of sealing on the outside will require a complex and time consuming operation, including removal of tubing and casing.
• The technology currently in use generally allows for cement logging behind one single tubular only. A technology allowing us to identify the cement height and quality behind dual tubulars (tubing and production casing) will significantly reduce time spent on casing removal.
How can we log through several layers of steel with the same orhigher level of interpretation quality as today?
CHALLENGE:
Preventing leak paths from control cables
How do we prevent leak paths from control cables, without having to pull the tubing?
Q:
CHALLENGE:
Preventing leak paths from control cables• The majority of our subsea wells have control lines/cables along the tubing down
to a valve or an instrumental piece of equipment. If we do not pull the tubing when doing P&A, these cables may become leak path sources if they are left in the well.
• Statoil’s internal requirements state: “Control cables and lines shall be removed from areas where permanent well barriers are installed, since they may create vertical leak paths through the well barrier.”
How do we prevent leak paths from control cables, without having to pull the tubing?
CHALLENGE:
Optimum well construction for future P&A
How can we simplify and improve the abandoment phase?Q:
CHALLENGE:
Optimum well construction for future P&A• When planning P&A and slot recovery operations we face numerous operational
challenges. Many of these could have been avoided if the initial well planning had incorporated other technology solutions. These may include :
− Positioning of completion components allowing us to leave the tubing in the well
− Optimum placement of cement
− Ways to log through multiple casings, e.g adding sensing materials to cement
− Avoiding barite settling for more efficient casing removal
− New materials/components for efficient section milling
− A game changing well construction enabling a full P&A on wireline
How can we simplify and improve the abandoment phase?
