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Debris Management and Cleanout - …

Debris Management and Cleanout Debris Categorization Solids Gunk (sludges, emulsions, viscous liquids , PIPE DOPE!) Junk introduced into the hole Source: Wellcert 1 Photograph (from Colombia) of cutter run. 2 Solids generated during the well construction process typified by: barite due to mud settlement cuttings (cement and formation) due to poor hole cleaning swarf from milling operations mill scale rust and other solids from poorly prepared tubulars 3 Gunk from fluids used in the well pipe dope tremendously damaging! viscous muds (milling fluids and synthetic muds at low temperature) gelled oil based mud after mixing with water 4 Junk introduced to the well: seals/elastomeric materials from BOP and seal stacks cement plugs and float equipment after drill out perforation Debris materials accidentally introduced : wood from pallets dropped objects hoses tools 5 Junk introduced to the well: Paint During lab test in Germany, (University of Hannover) we found out that 1 ft2 of paint could plug 1 ft2 of

Debris Management and Cleanout •Debris Categorization –Solids –Gunk (sludges, emulsions, viscous “liquids”, PIPE DOPE!) –Junk introduced into the hole

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Transcription of Debris Management and Cleanout - …

1 Debris Management and Cleanout Debris Categorization Solids Gunk (sludges, emulsions, viscous liquids , PIPE DOPE!) Junk introduced into the hole Source: Wellcert 1 Photograph (from Colombia) of cutter run. 2 Solids generated during the well construction process typified by: barite due to mud settlement cuttings (cement and formation) due to poor hole cleaning swarf from milling operations mill scale rust and other solids from poorly prepared tubulars 3 Gunk from fluids used in the well pipe dope tremendously damaging! viscous muds (milling fluids and synthetic muds at low temperature) gelled oil based mud after mixing with water 4 Junk introduced to the well: seals/elastomeric materials from BOP and seal stacks cement plugs and float equipment after drill out perforation Debris materials accidentally introduced : wood from pallets dropped objects hoses tools 5 Junk introduced to the well: Paint During lab test in Germany, (University of Hannover) we found out that 1 ft2 of paint could plug 1 ft2 of screens.

2 Sandro Sanchez Adrialpetro Ltd. 6 RISKS AND ISSUES Solids and junk result in inability to run the completion (early setting of packers) Solids and gunk have both caused problems functioning CIV/FIV type valves requiring bailer runs or coiled tubing intervention Gunk may produce serious formation damage Junk and solids can both prevent future well intervention activity or stick perforating guns Debris on top of wireline plugs can prevent their recovery 7 The Well Patroller one type of cleanup device designed to remove Debris from the well. 8 Learning Functioning the BOP with a clean fluid in the well can introduce junk Mixing water, brines, and particularly acid with OBM without suitable surfactants/solvents creates insoluble gunk (very viscous sludge) that prevented packers being set 9 10 Best Practices pt.

3 1 Proper preparation of tubulars to eliminate rust and mill scale polish prior to use. Careful fluid and hydraulic design to ensure effective hole cleaning and fluid compatibility The cleanliness of the wellbore should be confirmed by a gauge ring or drift sub using the clean up/workover string. Where there is concern about tubular condition (rust/mill scale/excessive doping/cement) pipe pickling should be considered. 11 TUBULAR: Size Weight Grade 3 1/2" # L 80 4 1/2" # L 80 5 1/2" 17# L 80 7" 29# L80 9 5/8" 47# L80 Total Average Scale In Pounds Per 1000ft. Millscale Deposition In Pounds Per Square Inch Source: Ramco, together with Robert Gordon's Institute of Technology, Wellcert 12 Mill Scale The formation of mill scale occurs on steel products in the manufacturing process.

4 When steel is heated to temperatures above approximately 600 C and its surface comes into contact with an uncontrolled atmosphere, oxidization takes place. When the steel is cooled down, the oxidization appears as scale. Oxidization takes place on any surface in contact with air during the manufacturing process. For tubular goods this means that both internal and external surfaces are affected. The action of rolling the pipe can force the scale to tightly adhere to the parent metal. Subsequent heat treatment to tubulars carried out in a furnace, without a controlled atmosphere, will add further deposits of mill scale. 13 Removal of Mill Scale in Pounds (of weight loss) PER 1000FT. TUBULAR: Size Weight Grade 3 1/2" # L 80 4 1/2" # L 80 5 1/2" 17# L 80 7" 29# L80 9 5/8" 47# L80 TREATMENT Internal Blast Cleaning (1) External Wire Brush (2) External Blast Cleaning (3) Difference Between External Blast and Wire Brush (3-2) Total Millscale/Corrosion (1+3) 14 Scale Density 1 cubic inch of scale in air weighs 1 cubic inch of scale in water weighs 15 Volume of Scale, in3 per 1000 ft of pipe (1728 in3 = 1 ft3) TUBULAR: Size Weight Grade 3 1/2" # L 80 4 1/2" # L 80 5 1/2" 17# L 80 7" 29# L80 9 5/8" 47# L80 Internal External Total 16 Best Practices pt 2.

5 Use optimum dope (manufacturer s recommendation) and torque to spec. Dope the pin, not the box. Function test BOP before placing on the well Keep the hole covered when not in use 17 Tools for Cleanup casing scrapers to remove cement and casing burs brushes to remove gunk and cement circulating subs to enable high circulating rates to be used junk subs to remove solids and junk jetting assemblies 18 Circulating Spacers and Displacement Pills Displacement pills designed to ensure effective mud displacement and water wetting of the casing in the event oil based muds are in use. Key roles: disperse and thin the drilling fluid (need compatibility with drilling fluids) lift out Debris and junk water wet pipe remove pipe dope effectively displace the mud 19 Issues Well control is key in pill sequence (only possible to get thin, light fluids in turbulence Pumping fluids to displace OBM without suitable surfactant packages may result in insoluble sludge Low temps can affect surfactant effectiveness Pills in turbulence lose carrying capacity if annular velocity drops below that required for turbulence 20 Issues In high mud weight, risk of inducing barite sag needs to be considered (displacement pills thin the mud to the point it can no longer support barite))

6 HSE needs to be considered for all chemicals used, mixtures of displacement pills and mud have to be separated from the active mud and packer fluid for disposal (zero discharge issues) 21 Learnings Conventional casing scrapers with spring actuated blocks have failed leaving junk in the hole or even a stuck tool. Conventional scrapers are not built for extended rotation or drilling. Scrapers work in reciprocation. Failure rate of multifunction ball opening circulating subs has been high in some regions. Weight actuated tools rely on maintaining weight set down on the tool to maintain the circulation path, all circulation is at one point. These tools should be run with the clutch option allowing drillpipe to be rotated independently of the pipe inside the liner.

7 22 Best Practices A casing scraper should create maximum contact with internal diameter of casing, (match strength of tools to string needs). Casing scrapers should enable rotation at rates up to 50 rpm. Scraper elements should be be capable of being lost in the hole. Circulating sub should be of weight set down type (clutch option). For a clean out strings in high angle cased and perforated well a Debris recovery system is best. Casing brushes are not considered necessary if an effective scraper is selected. If a brush is used it should be redressed after each application. 23 Filtration Filtration removes solids to prevent build up of solids and helps prevent plugging in the formation.

8 Two basic filtration systems are employed: cartridges (nominal or absolute) filter presses (Plate and Frame or Pressure Leaf) 24 Gel sample as pumped After Centrifuge Suspended fines in gravel pack or frac gel a problem? Washouts in washpipe (and screen) during packing 25 Risks and Issues Filtration can impact pump rate of completion fluids Filtration may be unnecessary cost in some wells, but should be assessed on a well-by-well basis (from potential damage mechanisms Filter presses have the advantage of high solids tolerance and throughput - units are large but cheap to operate. Cartridges used for small volumes of relatively clean material - smaller throughputs and less tolerance to dirty fluids, generally cartridges are more expensive Can be health and environmental risks associated with operating and disposing of filtration medium.)

9 26 Learnings units are not usually appropriate for dirty or viscosified fluids press materials require good HSE control is to over-specify filtration requirements. t filter oil with a DE press. less required when underbalance perforating(?) pills are usually not filtered cartridge filters are 2-5 times cost of nominal and usually worth it, but check bed filtration first. 27 Best Practices For general applications, coarse filtration to 80 microns is all that should be considered when fluids do not penetrate the formation When a fluid penetrates the formation, filtration is more likely to be required. Filtration should be tailored to the pore throat size of the formation. A simple guide to setting a specification is 14% (1/7th) of the average pore throat diameter Filtration below 2 microns is usually impractical Always use a guard filter downstream of a DE press For a DE press filtration, rate is approximately 1 bpm per 100 sqft for sea water and bpm per 100 sqft for a brine 28 Determination of Well Cleanliness The determination of how clean the well is usually based on the cleanliness of fluids returning from the wellbore.

10 The most common measures are normal turbidity units (NTU) and solids content, neither relate to what is left in the well. Junk baskets, gauge rings and the SPS WellPatroller do give some positive indication of solids removal. Other indicators of a clean well are torque and drag (related to the friction coefficient of fluid coating the casing walls) and cleanliness of the clean up string when pulled. 29 Risks and Issues NTU (a light transmission test) measurements rely solely on the cloudiness of the fluids, corrosion products in return fluids give high values, NTU and solids content are not directly related. Solids content will only assess materials collected at the bottom of the test tube during centrifuging.


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