Fundamentals of Drilling Course Outline (1)Basics of Rotary Drilling (2)Rotary (2) Operations/Coring Rotary Operations/Coring (3)Directional -Drilling Drilling (4)Fishing-Roundtrip (5)Casing/Cementing -Casing (6)Well Control -Coring (7)Principles of Drilling Fluid Technology (8)Principles of Borehole Stability (9)Principles of Hydraulic Testing
Major Rotary Operations Operation Result Operational Steps Drilling/Coring Making Hole/ Cutting Core Applying Weight on Bit (WOB) Rotating the Bit Circulating Fluid Adding Drillpipe Roundtrip Casing Cementing Lengthening the Drillstring Changing the Bit Borehole protected by casing Sheath of Cement in Annulus Screwing a new joint of drillpipe to the drillstring Circulation stopped Pulling-Out/Running-In the complete Drillstring Circulation stopped Running in Casing-Pipe Joint by Joint Pumping cement slurry in annulus
Major Rotary Operations - Drilling Controlling WOB by Drillometer
Controlling WOB with a Heave Compensation System Floating Drillship
Drillers Console Controlling WOB manually with brake lever Controlling WOB with Joystick
Major Rotary Operations Adding Drillpipe Conventional Method (manually)
Suspending the Drill String in the Rotary Table by Slips Working Principle of Rotary Slips
Screwing/Unscrewing Drillpipe Manually by spinning chain and Rotary Tongs Automatically by Iron Roughneck
Major Rotary Operations - Roundtrip Conventional Method (manually)
Rig Components used for manual Pipe Handling
manually Roundtrip Operation with Pipe Handling System
Open Hole DC Bit Reasons for Casing the Hole Casing is a string of single steel pipes with length of 8 16 m connected by threaded couplings Types of Casing Connections Casing is specified by Outer Diameter of Casing Pipe Weight per foot (wall thickness) After Grade Running of Steel CasingLoss Zones Cement Type of Slurry Coupling is pumped up the annulus in order to build up a Cement Sheath Bottom Cement
Casing Design Criteria (1) (2) (3) Tension/Joint Internal External Pressure Strength (Burst) (Collapse)
Cement Casing Shoe Liner Hanger Drilling and Casing Program 20 Conductor run in anda borehole is a telescope-like Pipe cementedconstruction to surface while preparing the wellsite (30 Each casing set reduces the 50 m Depth) DC 13 3/8 Surface Casing diameter thatcanbedrilled Drilling cemented to surface Purpose of through Conductor later Pipe 17 ½ Hole Bit 17 ½ Hole Purpose Channel for of circulating Surfacedrilling Casing fluid Diameter reduction is due to required Seal Prevents clearances off surface erosion freshwater of hole around base 17 ½ Drilling 12 ¼ Hole Provide Two of the Types rig attachment of Clearances of BOP s Anchoring Partial support Point for of Casing wellhead Hangers loadsfor 12 ¼ Hole Purpose of Production DC Sometimes further Purpose attachment Strings of Intermediate of Blowout 9 5/8 Intermediate Casing Support Preventers Casing for further (BOP) Casing/Tubing Bit Casing Isolate Isolate borehole Production formations from washouts Reservoir Bit Diameter/Inside Diameter containingof and high Casing cave 12 ¼ Drilling -inliner Protective Housing of Tubing Minimum: Strings pressure String fluids 3/32 or 2.38 mm Abbreviated 8 ½ Hole Isolate Attachment drilling String fluid of casing of Surface loss zones hung inside Production 8 ½ Hole the Stabilize preceding Equipment poorly casing consolidated string (usually formations 30 - Borehole 8 ½ Hole 150 DC Isolate m above Wall/Outside salt casing formations shoe) Diameter by a Liner of Casing 7 Production Casing Hanger Coupling Protection Casing in case of drilling very DC Bit 7 Liner Can deep be designed as intermediate or production string 8½ Drilling Drilling 5 7/8 Hole
Planning Rules for Drilling and Casing Program A good drilling and casing program is a decisive factor for technical and economical success of a drilling project Planning starts with the minimum borehole or casing diameter required at target depth Number of intermediate casings and depths of casing shoes are determined in dependency of the preliminary geological profile moving up progressively to surface Bit Diameters and Casing Diameters are standardized They have to be selected according to given sizes
Pressure-Depth Diagram for Determination of Casing Shoe Depth
Selection Guide for Drilling and Casing Program
Dependency of Drilling Costs on Borehole Diameter Experiences from Oil/Gas Exploration wells Conventional Slim Hole
Benefits of Slim Hole Drilling!Hole Diameters reduced by 50%!Requires smaller rigs!site reduced by 75%!Overall costs reduced by 40-50%
Slimhole Drilling with Coiled Tubing Technology
Principles of Core Drilling Area to be cut Bit Diameter Roller Cone Bit Core Barrel Core Bit Core Diameter Instead of cutting the total crosssectional area only an annular ring or kerf of rock is cut leaving a solid cylinder of uncut formation passing intothecorebarrel above the bit Key Components!Core Bit!Core Barrel!Retrieving Eqipment
Reasons for Core Drilling 1 Coring is the only way to supply intact specimens of the formation anatomy 2 In Hard Rocks Core Drilling can be a very efficient way to make a hole at good penetration rates and low costs Performance Parameter of Coring Operation!Core Recovery (%):!Core Quality Length of Core Length of Core Run
Oilfield Drilling Core Drilling Techniques Diamond Drilling Area to be cut Rotary DP Tooljoint Internal/ External Upset Large Annular Clearance Narrow Annular Clearance Oilfield Drilling Core Bits Area to be cut Hole Diameter Thick Kerf Oilfield Core Bit Diamond Core Bit Thin Kerf Diamond Drilling Core Bits
Influence of Kerf Width on Performance of Diamond Core Bits Core Bit Life Avg. Rate of Penetration Area Ratio Hole/Core Area Ratio Hole/Core
Types of Thick Kerfed Rotary Core Bits Used in KTB-VB Surface Set Diamond Bit PDC-Diamond Bit 4- and 6-Roller Cone Bit
Types of Diamond Drilling Core Bits Diamond Wireline Core Bits used in KTB-VB No Wireline Surface Set Diamond Bit Impregnated Diamond Bit Thin Kerfed Impregnated Diamond Core Bit
Performance of Core Bits in Crystalline Rock 6 Impregnated Diamond Core Bit 10 5/8 Roller Cone Core Bit KTB-VB Average Core Recovery: 97,8% Average Core Recovery: 42,9 %
Large Diameter Diamond Coring in KTB ultradeep Hole 12 ¼ Hole Section (6013-8328 m) Large Diameter Core 9 ¼ (234,7 mm) Core from KTB Pilot Hole
Diamond Bits recommended for various Rock Types
Recommended Diamond Stone Sizes for Various Rock Types SPC = Stone per Carat (0,2 g) Set Pattern for Diamond Stones
Optimal Rotational Speed for Diamond Core Drilling Ideal Peripheral Speed: 2 3 m/s Standardized Diamond Drilling Sizes
Single Tube Rotating Core Barrel Double Tube Advantages Advantages very Recovery Simple Can Corecanberetrieved rugged used Design with thin Enables and core of rugged unconsolidated orientation Construction available formations Easy kerfed by wireline Bits CoreOperation is marked Rotaryby Hole Sizes Encloses thin Good VeryCore and quality orienting kerfed efficient shoe Bits protects operation with usable knives the core Disadvantages In Good Disadvantages a shrink for hard fit rubber and compact tube rock thick Not Disadvantages Disadvantages kerfed available bits for Bad Disadvantages rotary Complicated Requires performance hole size thicker operation kerfed in Crystalline Complicated Disadvantages bits hard operation Poor Performance rock in friable/fractured rock frequent core blocks Types of Core Barrels Main Components!Outer Core Barrel Stationary!Inner Core Barrel!Core Lifter (Catcher)!Thrust Bearing!Ball Valve Oilfield Diamond Drilling WL-Retrievable Rubber Sleeve Oriented Threaded Head Tube Core Lifter Bit
Schematic of Core Catcher Spring Type Core Catcher Shoe of Inner Barrel Bit Core is lifted after ínner core barrel is filled by lifting the outer barrel which subsequently is transferred to the inner barrel (force for catching the core is supported by the outer barrel) wedging the core in the core lifter
Drill Rods for Diamond Drilling Drill Rods are standardized for Diamond Drill Rods Diamond Drilling Hole Sizes are externally flush with High Grade Hole Steel Size Couplings flush coupled pin to pin RW 1 25,4mm EW 1 ½ 38,1 mm AW 2 50,8 BW 2 ½ 63,5 NW 3 76,2 HW 4 101,6 Narrow Annular Clarance KTB 5 ½ WL-Drillpipe
Nesting of Casing with Standardized Diamond Drilling Sizes
Mechanism of Core Jamming Consequences of Core Jamming!premature tripout of core barrel (additional roundtrip time)!damage of core if not recognized Core Jamming Indicator
Mechanism of Core Jamming Indicator Valve Spring loaded flow path open Drilling Fluid Spring loaded flow path reduced Spring Bearing Inner Core Barrel Inner barrel is pushed up Bit normal coring operation Core jammed in inner barrel
Average Core Run Length in KTB-Pilothole Core Run Length (m) 10 5/8 Roller Cone 480 Depth (m) Length of inner Barrel: 9 m Sillimanite-Gneiss Directional Drilling (not cored) Amphibolite Cataclastic Sillimanite-gneiss Core Bits without Core Jamming Indicator 6 -Diamond Core Bit with Core Jamming Indicator Length of Wireline Core Barrel: 6 m Amphibolite Sillimanite-gneiss with amphibolites Amphibolite with metagabbro
Reasons for Wireline Coring Time for Drilling and Retrieving Core (min/m) Formation: Argillite Time Savings dependent on!bit Life of Wireline Core Bit!Core Run Length!Depth NXL Double Core Barrel Time Savings NX Wireline Core Barrel Depth (m)
Schematic of Wireline Core Barrels Latching Mechanism Overshot Bearing Outer Barrel Reaming Shell Inner Barrel Bit
Steps of Wireline Coring Operation Coring Assembly on Bottom ready for Core Run Inner Running CoreIn Barrel Overshot Retrievinglatched Inner filled Overshot up with on core WL On Core inner Barrel corebybarrel wireline Pumping In empty inner Core Barrel