This document discusses casing, which is large diameter pipe inserted into recently drilled boreholes and cemented in place. Casing serves several important purposes in the well construction process, including preventing contamination, cave-ins, and blowouts. Proper casing design considers formation pressures and strengths to determine optimal casing depths and diameters. Wells typically include multiple casing intervals of progressively smaller diameter to reach total depth. Casing is run and cemented in stages to safely drill to target depths.

1. UNIVERSITY OF
TECHNOLOGY
&
MANAGEMENT

2. GROUP MEMBERS
• ANKIT KUMAR
• BHANU MITRA
• DUSHYANT SHUKLA
• GARGI
• KUMAR ASHISH

3. CASING

4. What is CASING ?
• CASING IS LARGE DIAMETER PIPE THAT IS ASSEMBLED AND
INSERTED INTO A RECENTLY DRILLED SECTION OF A BOREHOLE
AND TYPICALLY HELD INTO PLACE WITH CEMENT.
• CASING IS THE MAIN PART OF THE WELL CONSTRUCTION. ALL
WELLS DRILLED FOR THE PURPOSE OF OIL OR GAS PRODUCTION
(OR INJECTING MATERIALS INTO UNDERGROUND FORMATIONS)
MUST BE CASED WITH MATERIAL WITH SUFFICIENT STRENGTH AND
FUNCTIONALITY.

5. PURPOSE OF CASING
• CASING THAT IS CEMENTED IN PLACE AIDS THE DRILLING PROCESS IN SEVERAL WAYS:
• PREVENT CONTAMINATION OF FRESH WATER WELL ZONES.
• PREVENT UNSTABLE UPPER FORMATIONS FROM CAVING-IN AND STICKING THE DRILL STRING OR
FORMING LARGE CAVERNS.
• PROVIDES A STRONG UPPER FOUNDATION TO USE HIGH-DENSITY DRILLING FLUID TO CONTINUE
DRILLING DEEPER.
• ISOLATES DIFFERENT ZONES, THAT MAY HAVE DIFFERENT PRESSURES OR FLUIDS - KNOWN AS ZONAL
ISOLATION, IN THE DRILLED FORMATIONS FROM ONE ANOTHER.
• SEALS OFF HIGH PRESSURE ZONES FROM THE SURFACE, AVOIDING POTENTIAL FOR A BLOWOUT
• PREVENTS FLUID LOSS INTO OR CONTAMINATION OF PRODUCTION ZONES.
• PROVIDES A SMOOTH INTERNAL BORE FOR INSTALLING PRODUCTION EQUIPMENT.

6. Design of casing
• Based on subsurface data such as
formation pressures, strengths,
makeup and balanced against the
cost objectives and desired drilling
strategy.
• Strategic depths at which the hole will
need to be cased in order for drilling
to reach the desired total depth.

7. DEPTH VS.
DIAMETER
• WITH THE CASING SET DEPTHS DETERMINED,
HOLE SIZES AND CASING SIZES MUST FOLLOW.
• THE HOLE DRILLED FOR EACH CASING STRING
MUST BE LARGE ENOUGH TO EASILY FIT THE
CASING INSIDE IT, ALLOWING ROOM FOR
CEMENT BETWEEN THE OUTSIDE OF THE CASING
AND THE HOLE.
• ALSO, THE INSIDE DIAMETER OF THE FIRST
CASING STRING MUST BE LARGE ENOUGH TO FIT
THE SECOND BIT THAT WILL CONTINUE
DRILLING. THUS, EACH CASING STRING WILL
HAVE A SUBSEQUENTLY SMALLER DIAMETER.

9. • IN DRILLING TECHNOLOGY, CASING STRING IS A LONG
SECTION OF CONNECTED OILFIELD PIPE THAT IS
LOWERED INTO A WELLBORE AND CEMENTED. THE PIPE
SEGMENTS (CALLED "JOINTS") ARE TYPICALLY ABOUT 40
FEET (12 M) IN LENGTH, MALE THREADED ON EACH END
AND CONNECTED WITH SHORT LENGTHS OF DOUBLE-
FEMALE THREADED PIPE CALLED COUPLINGS.
CASING STRING

10. INTERVALS
TYPICALLY , A WELL CONTAINS MULTIPLE INTERVALS OF CASING
SUCCESSIVELY PLACED WITHIN THE PREVIOUS CASING RUN. THE
FOLLOWING CASING INTERVALS ARE TYPICALLY USED IN AN OIL
OR GAS WELL:-
• CONDUCTOR CASING,
• SURFACE CASING,
• INTERMEDIATE CASING (OPTIONAL),
• PRODUCTION CASING,
• PRODUCTION LINER.

11. Casing programs
• SOMETIMES THE WELL IS DRILLED IN STAGES CALLED A CASING
PROGRAM.
• HERE, A WELL IS DRILLED TO A CERTAIN DEPTH, CASED AND
CEMENTED, AND THEN THE WELL IS DRILLED TO A DEEPER DEPTH,
CASED AND CEMENTED AGAIN, AND SO ON.
• EACH TIME THE WELL IS CASED, A SMALLER DIAMETER CASING IS
USED.
• THE WIDEST TYPE OF CASING IS CONDUCTOR PIPE (30 TO 42
INCHES FOR OFFSHORE WELLS AND 16 INCHES FOR ONSHORE
WELLS).

12. • THE NEXT SIZE IN CASING STRING IS THE SURFACE CASING, WHICH
CAN RUN SEVERAL THOUSANDS FEET IN LENGTH.
• IN SOME WELLS, PROTECTION OR INTERMEDIATE CASING IS RUN
TO SEPARATE CHALLENGING AREAS OR PROBLEM ZONES( AREA OF
HIGH PRESSURE OR LOST CIRCULATION)
• THE LAST TYPE OF CASING STRING RUN INTO THE WELL , AND
SMALLEST IN DIAMETER, IS THE PRODUCTION OR OIL STRING.
• THE OIL STRING RUNS DIRECTLY INTO THE PRODUCING RESERVOIR.

13. CASING ALTERNATIVES
• IN AN EFFORT TO SAVE MONEY , SOMETIMES A LINER STRING IS
RUN INTO THE WELL INSTEAD OF A CASING STRING.
• WHILE A LINER STRING IS VERY SIMILAR TO CASING STRING IN
THAT IT IS MADE UP OF SEPARATE JOINTS OF TUBING , THE LINER
STRING IS NOT RUN THE COMPLETE LENGTH OF THE WELL.
• A LINER STRING IS HUNG IN THE WELL BY A LINER HANGER , AND
THEN CEMENTED INTO PLACE.

14. OIL RIG CASING
• AS THE PROCESS OF DRILLING CONTINUES, THEY
REACH THE PRE-SET DEPTH (ANYWHERE FROM A
FEW HUNDRED TO A COUPLE-THOUSAND
FEET),THEY MUST RUN AND CEMENT THE CASING
PIPE SECTIONS INTO HOLE TO PREVENT IT FROM
COLLAPSING IN ON ITSELF.
THE CASING PIPE HAS SPACERS AROUND THE
OUTSIDE TO KEEP IT CENTERED IN THE HOLE.

15. • CASING IS RUN FROM THE RIG FLOOR, CONNECTED ONE JOINT AT A
TIME BY CASING ELEVATORS ON THE TRAVELLING BLOCK AND
STABBED INTO PREVIOUS CASING STRING THAT HAS BEEN INSERTED
INTO THE WELL.
• CASING A RIG ALSO INVOLVES RUNNING STEEL PIPE DOWN THE INSIDE
OF A RECENTLY DRILLED WELL.
• THE SMALL SPACE BETWEEN THE CASING AND UNTREATED SIDES OF
THE WELL IS FILLED WITH CEMENT TO PERMANENTLY SET THE CASING
IN PLACE.

16. CASING DRILLING TECHNOLOGY
• CASING DRILLING IS AN ALTERNATIVE OPTION FOR CONVENTIONAL
DRILLING AND USES STANDARD OILFIELD CASING INSTEAD OF
DRILL STRING.
• THIS TECHNOLOGY IS ONE OF THE GREATEST DEVELOPMENT IN
DRILLING OPERATIONS, AND INVOLVES DRILLING AND CASING A
WELL SIMULTANEOUSLY.
• CASING DRILLING CAN REDUCE DRILLING TIME BY 20 TO 30%, AND
ALSO HAS GREATER BOREHOLE STABILITY AND WELL CONTROL.

17. THANK YOU….