Sustained Casing Pressure (SCP) - The good, the bad and the ugly.
Simon Sparke
Providing well integrity training and consultancy across all well types, ages, classifications and locations.
For many years the issue of SCP has been a well integrity discussion subject, much talked about and often quoted. Burgoyne, Hopmans and Vinges have all been published with the various numbers of wells in GoM, Global and Norway, and the numbers are high, but still persist and quite probably continue to rise.
The issue is most certainly on the agenda of various regulators; some of whom expect good management and mitigation, and others who demand it to be resolved quickly or face the consequences.
API-90 makes it quite clear where SCP begins and ends, but understanding the issue and its possible remediation alternatives takes a deeper and more involved position. It takes time to understand, collate data and ultimately determine how the problem may be resolved.
Various logging companies can sell surveys that will tell where the problem starts, on which annulus and will provide coloured plots, temperature logs and more. But please always insist on seeing the calibration before running the log, and ensure that the survey is fully supervised and planned by the Operator.
Clearly though, Operators seek to not only understand the problem, but also find a remediation process that is effective, timely and preferably non-intrusive, so that risks are minimised and the well continues on production.
The application of heavy brines to mitigate SCP has merit and has proved successful - if correctly managed.
However, in recent courses and work environments I have been in discussion with Operators who have tried unsuccessfully to use heavy weight brines simply expecting rapid results. In some cases bleeding off annulus pressure through 3’’ chicksans thinking it will get rid of the problem quickly. When all the papers strongly suggest taking time, bleeding off slowly and above all collecting bleed down and subsequent build up data. Just using a cement pump, injecting brine quickly and expecting quick communication and resolution to the problem is not the answer.
What they didn’t expect was the problem to get worse. For one Operator, this resulted in several wells having parted tubulars and very serious pressure problems to surface. Evaluation of the physical, chemical and hazard characteristics of the brine had not been carried out. Density, viscosity, pH, buffering and corrosivity all need consideration for a successful intervention. SCP mitgation is above all a safety issue and putting people and the environment in harm’s way by using toxic fluids to fix the problem simply increases risk and should be avoided.
In all instances, when a fluid is being added it is srongly recommended to get the advice of specialists.
Understand the problem → Plan the intervention → Specify the brine and injection unit → Risk assess the product and process → Execute the plan.
For advice and guidance on SCP mitigation and brine selection, Well Integrity, WIMS and Policies I can be contacted via LinkedIn and by E-mail [email protected].
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Petroleum Engineer (Well Integrity)
4 年Good peace of knowledge
Business Development Manager
4 年Hello Simon. Good piece. Lets have some personal discussion . Regards
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Well Integrity & Remediation SME
4 年Thank you Simon for bringing this subject up. It can't be stressed enough that one has to do their homework to understand the real issues at work when dealing with SCP in both cased hole sections and open hole sections of wellbores. There are a lot of things that can influence the source of the pressure and the channels in which the pressure gets to surface. In wellbores with open hole sections, buildup tests can be dangerous if not closely monitored and vetted by professionals who can actually make sense of the data. In any type of annular gas migration scenario you have to look at at all wellbores in an aerial proximity to see what may be gleaned from their data. Case in point on a land based drilling operation. Operator drills a new well and has significant gas flow outside of intermediate casing and can't determine the source using Carbon 13 Isotope analysis. There was an offset well 200 meters away that was cored and lithologged in its entirety from surface to 1000+ meters with gas detection equipment in use and no one..... even looked at the data. Homework is critical... You don't get a degree without it, unless you are absolutely brilliant at what you do and cognitive recognition skills that far surpass the masses.
Senior Quality Advisor at Ullensaker kommune
4 年Simon. Good article and I agree completely with your assessment and conclusion. When I headed up the Well Integrity section in Karachaganak in Kazakhstan, we used a wide range of techniques to suppress the SCP in the B and C annuli of these wells. These wells with SCP was drilled back in the 80 and 90 under the FSU “Influence”. The best result we found was to use a heavy, non-damaging fluid to manage the SCP. We ended up in using the CASEGUARD .i.e. the Cesium Formate brine with an adjusted density to 1,96 SG ( Temperature determined). This fluid will manage the SCP, but will never remove it complexly and these well needed a constant monitoring and follow-up on a regular basis