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!

2 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.

3 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.

4 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. 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.

5 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.

6 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.

7 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.

8 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. 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.

9 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.)

10 Risk of inducing barite sag needs to be considered (displacement pills thin the mud to the point it can no longer support barite) 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.