Bai giang pttkk drilling fluid circulation system

Drilling Fluid Circulation Systems Introduction Mud Pumps Duplex PDP & Triplex PDP Solids removal Solid Control Equipment 4.1 Shale shakers 4.2 Degasser 4.3 Mud Cleaners Treatment and Mixing Equipment References (CDF) Jorge H.B Sampaio Jr “Drilling Engineering Fundamentals.” Master of Petroleum Engineering Curtin University of Technology, 2007 Chapter 2 (WEC) Rabia, Hussain “Well Engineering & Construction” Entrac Consulting Limited, 2002 Chapter & 16 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Introduction 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Drilling Fluid Roles ✓ The drilling fluid plays several functions in the drilling process ✓ The most important are: ➢ clean the rock fragments from beneath the bit and carry them to surface ➢ exert sufficient hydrostatic pressure against the formation to prevent formation fluids from flowing into the well ➢ maintain stability of the borehole walls ➢ Cool and lubricate the drillstring and bit 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Drilling Fluid Circulation ✓ Drilling fluid is forced to circulate in the hole ➢ at various pressures and ➢ flow rates ✓ Drilling fluid is stored in steel tanks located beside the rig ✓ Powerful pumps force the drilling fluid through surface high pressure connections to a set of valves called pump manifolds located at the derrick floor 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Drilling Fluid Circulation (Cont) ✓ From the manifold, the fluid goes up the rig within a pipe called standpipe to approximately 1/3 of the height of the mast ✓ From there the drilling fluid flows through a flexible high pressure hose to the top of the drillstring ➢ The flexible hose allows the fluid to flow continuously as the drillstring moves up and down during normal drilling operations 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Swivel ✓ The fluid enters in the drillstring through a special piece of equipment called swivel located at the top of the kelly ➢ The swivel permits rotating the drillstring while the fluid is pumped through the drillstring 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Drilling Fluid in Wellbore ✓ In wellbore ➢ The drilling fluid then flows down the rotating drillstring and jets out through nozzles in the drill bit at the bottom of the hole ➢ The drilling fluid picks the rock cuttings generated by the drill bit action on the formation ➢ The drilling fluid then flows up the borehole through the annular space between the rotating drillstring and borehole wall 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Drilling Fluid at Surface ✓ At surface ➢ At the top of the well (and above the tank level), the drilling fluid flows through the flow line to a series of screens called the shale shaker ❖ The shale shaker is designed to separate the cuttings from the drilling mud ❖ Other devices are also used to clean the drilling fluid before it flows back into the drilling fluid pits 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com Process of Mud Circulation ✓ The principal components of the mud circulation system are: ➢ Pits and tanks, ➢ Pumps, ➢ Flow line, ➢ Solids and contaminants removal equipment, ➢ Treatment and mixing equipment, ➢ Surface piping and valves, ➢ The drillstring 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com The Tanks ✓ The tanks (3 or – settling tank, mixing tank(s), suction tank) are made of steel sheet ➢ They contain a safe excess (neither too big nor too small) of the total volume of the borehole ❖ In the case of loss circulation, this excess will provide the well with drilling fluid while the corrective measures are taken ➢ The number of active tanks depends on ❖ The current depth of the hole (bypasses allow to isolate one or more tanks.) ➢ The tanks will allow enough retaining time so that much of the solids brought from the hole can be removed from the fluid 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 10 Mud Cleaners ✓ Inert solids in weighted fluid (drilling fluid with weight material like barite, iron oxide, etc) can not be treated with hydrocyclones alone ➢ because the particle sizes of the weighting material are within the operational range of desanders and desilters ➢ Weighting material are relatively expensive additives, which must be saved 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 66 Mud Cleaner Schematic ✓ The mud cleaner separates ➢ the low density inert solids (undesirable ) ➢ from the high density weighting particles 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 67 Hydrocyclones ✓ Hydrocyclones discriminate light particles from heavy particles ➢ Bentonite are lighter than formation solids because they are of colloidal size (although of the same density) ➢ Barite particles are smaller than formation solids because they are denser ✓ The desilter ➢ removes the barite and the formation solids particles in the underflow, ➢ leaving only a clean mud with bentonite particles in a colloidal suspension in the overflow 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 68 Hydrocyclones (Cont.) ✓ The thick slurry in the underflow ➢ goes to the fine screen, which separate the large (low density) particles (formation solids) from the small (high density) barite particles, thus conserving weighting agent and the liquid phase but at the same time returning many fine solids to the active system ✓ The thick barite rich slurry is treated with dilution and mixed with the clean mud (colloidal bentonite) ✓ The resulting mud is treated to the right density and viscosity and re–circulates in the hole 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 69 Principle of The Mud Cleaner ✓ Mud cleaners ➢ are used mainly with oil–and synthetic–base fluids where the liquid discharge from the cone cannot be discharged, either for environmental or economic reasons ➢ may also be used with weighted water–base fluids ❖ to conserve barite and the liquid phase 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 70 Treatment and Mixing Equipment 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 71 Drilling Fluid Components ✓ Drilling fluid is usually a suspension of clay (sodium bentonite) in water ✓ Higher density fluids can be obtained ➢ by adding finely granulated (fine sand to silt size) barite (BaSO4) ✓ Various chemicals or additives are also used in different situations ✓ The drilling fluid continuous phase is usually water (freshwater or brine) called water–base fluids ✓ When the continuous phase is oil (emulsion of water in oil) it is called oil–base fluid 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 72 Drilling Fluids Physical Properties Blenders ✓ The basic drilling fluids physical properties are density, viscosity, and filtrate ➢ Fresh water density is 8.37 pounds per gallon (ppg) ➢ Bentonite adds viscosity to the fluids and also increases the density to about to 10 ppg ➢ Higher density (15 to 20 ppg) is obtained with barite, iron oxide, or any other dense fine ground material ✓ Tank agitators or blenders ➢ are located in the mud tanks ➢ to homogenize the fluid in the tank ➢ help to keep the various suspended material homogeneously distributed in the tank ❖ by forcing toroidal and whirl motions of the fluid in the tank 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 73 Mixing Equipment ✓ Water base fluids are normally made at the rig site ✓ (oil base mud and synthetic fluids are normally manufactured in a drilling fluid plant) ✓ Special treatment and mixing equipment exists for this purpose ✓ The drilling fluid continuous phase is usually water (freshwater or brine) called water– base fluids ✓ Tank agitators, mud guns, mixing hoppers, and other equipment are used for these purposes 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 74 Mud Agitator Tank agitator or blenders 01/2018 Toroidal and whirl motions Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 75 Sample of Mud Agitator 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 76 Mud Guns ✓ Mud guns ➢ are mounted in gimbals at the side of the tanks, ➢ allow aiming a mud jet to any point in the tank ➢ help to homogenize the properties of two tanks, and spread liquid additives in a large area of the tank (from a premixed tank) ✓ Centrifugal pumps power the mud guns 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 77 Mixing hopper ✓ The mixing hopper ➢ allows adding powder substances and additives in the mud system ✓ The hopper is connected to a Venturi pipe ➢ Mud is circulated by centrifugal pumps and passes in the Venturi at high speed, sucking the substance into the system 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 78 Mud Hopper 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 79 Mud Hopper 01/2018 Đinh Công Vĩnh Luân – MSc in Offshore Engineering Email: luandcv@gmail.com 80