Worlds First Offshore Horizontal Well Using Jointed Pipe Cemented Frac Sleeve Technology

2022 ◽  
Author(s):  
Shaun Thomson ◽  
Baglan Kiyabayev ◽  
Barry Ritchie ◽  
Jakob Monberg ◽  
Maurits De Heer ◽  
...  

Abstract The Valdemar field, located in the Danish sector of the North Sea, targets a Lower Cretaceous, "dirty chalk" reservoir characterized by low permeabilities of <0.5mD, high porosities of >20% and contains up to 25% insoluble fines. To produce economically the reservoir must be stimulated. Typically, this is by means of hydraulic fracturing. A traditional propped fracture consists of 500,000 to 1,000,000 lbs of 20/40 sand, placed using a crosslinked seawater-based borate fluid. The existing wells in the field are completed using the PSI (perforate, isolate, stimulate)1 system. This system was developed in the late 1980s as a way of improving completion times allowing each interval to be perforated, stimulated and isolated in a single trip and has been used extensively in the Danish North Sea in a variety of fields. The system consists of multiset packers with sliding sleeves and typically takes 2-3 days between the start of one fracture to the next. Future developments in this area now require a new, novel and more efficient approach owing to new target reservoir being of a thinner and poorer quality. In order for these new developments to be economical an approach was required to allow for longer wells to be drilled and completed allowing better reservoir connectivity whilst at the same time reducing the completion time, and therefore rig time and overall cost. A project team was put together to develop a system that could be used in an offshore environment that would satisfy the above criteria, allowing wells to be drilled out to 21,000ft and beyond in excess of coiled tubing reach. The technology developed consists of cemented frac sleeves, operated with jointed pipe, allowing multiple zones to be stimulated in one trip, as well as utilizing a modified BHA that allows for the treatments to take place through the tubing, bringing numerous benefits. The following paper details the reasons for developing the new technology, the development process itself, the challenges that had to be overcome and a case history on the execution of the first job of its kind in the North Sea, in which over 7MM lbs of sand was pumped successfully, as well as the post treatment operations which included a proof of concept in utilizing a tractor to manipulate the sleeves. Finally, the production performance will be discussed supported by the use of tracer subs at each of the zones.

2020 ◽  
Author(s):  
Ryvo Octaviano ◽  
Erik Hornstra ◽  
Jonah Poort ◽  
Pejman Shoeibi Omrani ◽  
Ruud van der Linden ◽  
...  

1996 ◽  
Vol 48 (5) ◽  
Author(s):  
Philip Wodka ◽  
Henrik Tirsgaard ◽  
C.J. Adamsen ◽  
A.P. Damgaard

2022 ◽  
Author(s):  
Asif Hoq ◽  
Yann Caline ◽  
Erik Jakobsen ◽  
Neil Wood ◽  
Rob Stolpman ◽  
...  

Abstract The Valhall field, operated by AkerBP, has been a major hub in the North Sea, on stream for thirty-eight years and recently passed one billion barrels of oil produced. The field requires stimulation for economical production. Mechanically strong formations are acid stimulated, while weaker formations require large tip-screenout design proppant fractures. Fracture deployment methods on Valhall have remained relatively unchanged since the nineties and are currently referred to as "conventional". Those consist in a sequence of placing a proppant frac, cleaning out the well with coiled tubing, opening a sleeve or shooting perforations, then coil pulling out of hole pumping the proppant frac. For the past few years, AkerBP and their service partners have worked on qualifying an adapted version of the annular coiled tubing fracturing practice for the offshore infrastructure - a first for the industry, which has been a strategic priority for the operator as it significantly reduces execution time and accelerates production. As with all technology trials, the implementation of this practice on Valhall had to begin on a learning curve through various forms of challenges. Whilst investigating the cause and frequency of premature screenouts during the initial implementation of annular fracturing, the team decided to challenge the conventional standards for fluid testing and quality control. Carefully engineered adjustments were made with regards to high shear testing conditions, temperature modelling, and mixing sequences, these did not only identify the root cause for the unexpected screenouts, but also helped create the current blueprint for engineering a robust fluid. Since the deployment of the redefined recipe, adjusted testing procedures and changes made to the stimulation vessel, there have not been any cases of fluid induced screenouts during the executions. The fewer types of additives now required for the recipe have lowered the cost of treatments and the lower gel loading leads to reduced damage in the fractures, thereby contributing to enhanced production over the lifetime of the wells. This paper describes the investigation, findings and the resulting changes made to the fluid formulation and quality control procedures to accommodate for high shear and dynamic wellbore temperature conditions. It discusses the rationale behind the "reality" testing model and, proves that significant value is created from investing time in thoroughly understanding fluid behaviour in the lab, prior to pumping it on large-scale capital-intensive operations. The study demonstrated that there is always value in innovating or challenging pre-conceived practices, and the learnings from this investigation significantly improved the track record for annular fracturing on Valhall, redefined fluid engineering for the North Sea and will inform future annular fracturing deployments on other offshore assets around the world.


1970 ◽  
Vol 64 (2) ◽  
pp. 229-240 ◽  
Author(s):  
Wolfgang Friedmann

The decision of the International Court of Justice in the North Sea Continental Shelf Cases is surely one of the most interesting as well as debatable decisions in the history of the Court. It deals with certain aspects of one of the most important new developments of international law, the doctrine of the Continental Shelf. It also touches on some basic problems of the sources of international law. Among the matters dealt with, in greater or lesser detail, by the Court are the formation of custom in contemporary conditions, the effect of custom upon treaty and, in turn, the possible translation of principles formulated in a multilateral treaty, into universal custom. Above all, the Court was compelled to formulate certain principles of general equity as applicable to the delimitation of the continental shelves between three of the coastal states of the North Sea. It is this attempt of the Court to formulate the general principles of equity applicable to a fair allocation of the resources of the Continental Shelf between neighbors with which the present article will be mainly concerned.


1991 ◽  
Author(s):  
C.W.J. Hoyer ◽  
A. Chassagne ◽  
B. Vidick ◽  
I.P. Hartley

2007 ◽  
Author(s):  
Rodney Alan Farquhar ◽  
Frank Rattray ◽  
Alex Annandale ◽  
Alan Reid ◽  
Steve Glegg

1996 ◽  
Vol 48 (05) ◽  
pp. 406-413 ◽  
Author(s):  
Philip Wodka ◽  
Henrik Tirsgaard ◽  
C.J. Adamsen ◽  
A.P. Damgaard

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