Drilling & Production

A successful completion of the longest deepwater horizontal gravel pack (HZGP) was performed by placing 75,000 lb of gravel for an operator in offshore Brazil.

Brazil's long deepwater horizontal gravel pack

A successful completion of the longest deepwater horizontal gravel pack (HZGP) was performed by placing 75,000 lb of gravel for an operator in offshore Brazil. Halliburton Serviços Ltda completed the HZGP in a 832-meter openhole section in 799 meters water depth. Despite the long slant section (2,000 meters @ 60 degrees) and openhole length, installation of the sand control completion was successful, never exceding more than 10,000 lb of drag.

Increasing net reserves through extended-reach horizontal wells can present additional challenges to operators in deepwater. Matching computer simulation, using HzGPSim software, to job design was instrumental in the execution of the gravel pack placement, Halliburton engineers claim.

Spiral centralizers were used to reduce drag during installation and lift the long horizontal screen section off the low side of the hole, enabling uniform placement of the gravel pack over the entire interval. After the gravel packing was completed, the lower end screen section was isolated by a proprietary screen plug assembly, which prevents sand production from potentially exposing the lower section of the open hole.

This technological achievement demonstrated the ability to increase long-term production reliability and net reserves through the uniform placement of a highly permeable sand filter around a mechanical mesh filter over a long horizontal section.

Longest CT-conveyed perforating assembly

A coiled tubing conveyed perforating record was carried out on behalf of Talisman Energy UK Limited. The operation took place on the Talisman Energy's Clyde Platform in the North Sea, with 2,840 ft of 2-1/2 in. perforating guns run in, and reverse-deployed, in a single run to depths of about 17,800 ft. BJ Services Well Services Division for the Europe-Africa Region undertook the operation.

The operation presented logistical and technical challenges involving 18,500 ft of 2-in. coiled tubing which was shipped on a lightweight transport carrier, and spooled onto the work reel on board. The perforated interval was the Southern Horst A Zone sands - or SHAZ - located within the Fulmar formation.

The heel-to-toe zone of the well featured 2,500 ft of horizontal 4-1/2-in. liner, with a maximum deviation of 97 degrees. Engineering simulations for the coiled tubing run prior to the operation also highlighted the need for a metal-to-metal friction reducer to be introduced in the well, in order to facilitate transport of the perforating guns to the end of the well. The long length of perforating guns, coupled with the configuration of the well, posed a number of challenges. The coiled tubing team believes the operation to be the longest coiled tubing conveyed perforating assembly.

Milestone: 1,000 ft of perforated hole

A new milestone has been set - 1,000 ft of production perforating in a well using a slickline perforating system. The depth measurement on the operation was with an accuracy of +/- 2 ft. The operation was planned over a period of two years. Previously, Expro Inter-national Group, which undertook the operation, had perforated over 26 wells in the North Sea, Thailand, China, and the US using slickline. Expro claims the system has been used by Shell, BP, Phillips, ExxonMobil, Conoco, Unocal, and Lasmo.

As part of a broader 'slickline revolution' initiative, Expro claims the use of slickline for cost-effective perforating has been successful onshore and offshore. The system uses a hollow carrier or strip gun assemblies, as well as various combinations of wire types and sizes to suit any well or downhole condition. Expro stated that the operation improved the accuracy of depth measurement of perforating operations.

Design, evaluation tool for new, existing wells

An Aberdeen engineering company claims it has developed a well construction system that can enhance drilling performance by predicting wellbore stability and hole cleaning related problems. The result follows four years of research and development integrating statistical methodologies with fluid dynamics and geomechanics.

Innovative Engineering Systems Ltd's (IESL) system, known as GeoDRILL, is a methodology designed to optimize the drilling process through analysis and statistical field validated models. IESL says the system can be used as a design or evaluation tool for drilling of new or existing wells. For example, this would include providing operators and contractors with information on optimum mud weights required for drilling through problematic shales, unconsolidated sections or severely depleted reservoirs. Drilling fluid flow rates and properties required to ensure maximum hole cleaning can also be determined, which helps to avoid costly and sometimes catastrophic consequences, such as stuck pipe, high drag and torque or even complete loss of the well.

The system is composed of three main modules - Drill Cutting Size Determination, Computational Fluid Dynamics, and Geomechanical Model - and can be used in various phases of the drilling operation. Used in the planning stages and in early operation when problems become apparent, the system can conduct daily monitoring and give advance warning of instability and hole cleaning problems, the developers say.

The system is mainly for well drilling operations but can also be used to enhance hole cleaning by ensuring effective transport of drill cuttings to the surface. By optimizing the properties of the drill fluid, the ROP (rate of penetration) is maximized, by avoiding valuable rig time spent backreaming, or circulating for long periods of time.

Further, the developers claim the system predicts stability and hole cleaning related problems and determines the optimum operational conditions to overcome the problems. The ability to determine the drill cuttings size also enables it to evaluate optimum disposal options, such as discharge overboard or re-injection. It has been successfully used in over 40 wells in the North Sea, West Africa, Latin America and the Far East.

Ability to control unwanted water

Unwanted water and gas production and disposal can be a huge problem globally, with most wells producing more water than oil. The ability to control unwanted water and gas insitu can mean the difference between an economic well and a plugged one. Halliburton claims it is increasing the economic life of reservoirs by combining reservoir understanding and innovative placement technique, with a conformance solution such as the H2Zero.

The first application of the technology was completed in the Gulf of Mexico. The solution was applied to an Exxon-Mobil-operated well in the Mississippi Canyon Field, which had previously been shut in, due to excess water production. The 96% reduction in the water-to-gas ratio (WGR) greatly exceeded the expected, or "most likely," results (50%).

Controlling the placement of the solution in what has historically been a difficult environment to do so (a gravel pack completion) was a critical component of the overall process at the Gulf of Mexico field. Employing a novel approach with the utilization of a temporary plug to protect the productive gas interval and using coiled tubing to place the treatment resulted in a successful application. Afterwards, the plug was removed.

Originally developed for the North Sea, the solution employs an environmentally sensitive polymer system that provides capabilities for controlling unwanted water and gas production. The firm says the system has performed consistently at temperature ranges up to 300°F.

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