1. Petro Data Mgt II- Drilling and Production
Petroleum Professor
Collins Nwaneri

2. Drilling Geology
Overview – geology as it relates to drilling operations and basic principles of hydrostatic pressure exerted by a fluid at depth as it is important for drilling operations.
Types of Rocks:
1. Igneous rocks – Formed by molten rock cooling and solidifying.
what are examples of Igneous rocks?

3. Continued
Sedimentary rocks – Formed by digenesis (chemical changes) or cementation of sediments.
Metamorphic rocks – Formed by the physical changes of existing rocks by high pressures and temperatures.
which of this rock type is likely to be a better source rock and why?

4. Continued
Plate Tectonics – solids plates found underneath the earth surface floating on top of liquid rock or molten rock.
Movement of the plates leads to rocks moving up or down within the earth crust. It can also need to rock beds becoming folded, broken and turned over. Fluid pressure and stresses within the rock will vary.
Two major types of rock movements are:
1. Thrust fault (rocks are compressed together) to move in what direction?

5. Continued
Normal fault(rocks are stretch apart) to move in what direction?

6. Lithology
Lithology- a description of rocks that is based physical characteristics such as mineral comp, color, grain size and texture.
Lithology affects many drilling decisions when planning and drilling a well.
Examples of some lithologies:
1. Shale- consists of layers of clay minerals. They form about 75% of sedimentary rocks. Shale cause about 90 % of geology related drilling problems.
What will happen if water based drilling mud is used to drill reactive shale formations?

7. Continued
2. Sandstone – consists of particles of sand (quartz), and maybe with traces of other minerals, such as iron. - clay minerals can also be found within sandstone if found within sandstone, how will it cause problems? - 11% of sedimentary rocks are made up of sandstone. Sandstone or other rocks must have porosity and permeability in other to be a reservoir.

8. continued What is a reservoir and define porosity and permeability?
How is the porosity and permeability for sandstone and shale?
Yes or no…..can a rock have permeability but no porosity.
3. Carbonates – composed of fossilized skeletons and minerals grains of calcite (crystals of calcium carbonates). Example is limestone. They are crystalline limestone and fossiliferous limestone.
what is the difference between them? Most limestone's are fossiliferous.

9. Continued
- Carbonates are often fractured due to their brittle nature. Fractured carbonates make prolific reservoir rocks as oil and gas collect in the fractures
They have high permeability and can produce high rates of hydrocarbons if intersected in a drilled well.
can also loose drilling fluids into the formation due to the fractures. Carbonates make up 13% of sedimentary rocks

10. Continued
3. Evaporates (salts) – occurs as result of sea water evaporating, leaving behind soluble salts. Less soluble salts are deposited first out of solution. Very soluble salts come out when dehydration is almost complete. - Salts can cause drilling problems…True or false. How? - What can you pump to dissolve flowing salt around drill bits in a well that causes the bit to stop drilling? - salt dome are good trap for reservoirs hydrocarbons.

11. Rock Strengths and Stress
Rock strength varies depending on the types of stress applied on the rock (compressive, tensile or shear and may also vary due to the direction the stress is applied.
- Tensile stress is negative rock stress
Compressive stress is positive rock stress
Shear stress is up and down rock stress
Overburden stress – vertical stress due to weight of surrounding rocks.

12. Continued Stress distribution is affected by tectonic activities.
No or little tectonic activity …less horizontal compressive stress and high vertical compressive stress
With tectonic forces or other forces, stress differs.
Example basic stress distribution magnitude in disturbed horizontal and vertical wells?

13. Principal stress
Three stress resolved in perpendicular direction to each other. Two horizontal and one vertical stress. All compressive or tensile ( no shear stress).
- stress orientation is important in designing a well and procedure to drill it successfully.
Fracture pressure – rock ability to withstand pressure, which can cause tensile failure if not controlled.

14. Hydrostatic pressure
Fluid impose hydrostatic pressure in a well and if the downhole pressure is not kept under control, it can cause an uncontrolled release of hydrocarbons (Blowout).
Pressure is force/Area
When formation pressure is higher than is normal for a depth this is called Over pressured formation

15. Geological input to drilling wells
You need to know the relationship between hydrostatic pressure, fracture pressure and pore pressure for a successful drilling operations.

16. Oil and Gas Reservoir Formation
Overview – The processes involved in petroleum generation, migration and accumulation into an exploitable reservoir will be described . Important rock properties for reservoir creation and fluid properties within the reservoir will be described.
Hydrocarbons move upwards within the earth until they meet a barrier, and then may accumulate as an oil and gas reservoir.
If there is no barrier, then they migrate to the surface as oil seep.

17. Continued
They are seven main factors that all need to be present, in the right order, for a hydrocarbon accumulation to occur. These are the following:
Source rock
Hydrocarbon generation
Primary migration to a suitable structure (Reservoir)
Structural trap
Reservoir rock
Seal Rock
Secondary migration within the reservoir
Which of this factors can be best attributed to what is called a dry wellbore? Mention at least two man made factors that can result in a dry wellbore?

18. Source Rock and Hydrocarbon Generation
Buried remains of plant and animals accumulated over millions of years ago in slow moving or stationary water environments such as swaps, lakes, coastal regions and shallow seas.
These organic materials plus other non-organic particles (clay minerals, fine sands, and silts) sank to the bottom and resulted in a build up of sediments over a long period.
Increasing Temperature and Pressure with depth of this organic-laden sediments results to sedimentary rocks when they under go digenesis.

19. Continued
About 99 % of all hydrocarbons deposit are found in sedimentary rocks.
Chemical transformation also occur in the organic matter present in the pore spaces of the rock.
Oil is generated from organic remains under certain conditions, with temperature as the most important factor. Oil generation starts at 50 deg. C and conversion to oil peaks 90 deg C and stops at 175 deg C.
This temperature range between 50 deg C and 175 deg C is known as the oil window

20. Continued
The decay of organic remains that generate gas occurs at below and above the oil window.
Biogenic gas (generated by microbes) or swamp gas is generated at a temperature below 50 deg C.
Thermal gas is generated at above 175 deg C.
Heavy oil is generated at temperatures at the lower end of the oil window
At Increasing temperature, lighter (more valuable) hydrocarbons are generated.
At a high rock temperature of above 260 deg C, the organic mineral, which generates oil is destroyed.

21. Continued
Petroleum is made up of: (83%) Carbon and (13%) Hydrogen and sometimes with small amounts of sulfur (up to 2%), nitrogen (0.5%)
90 % of most crudes oils contain hydrocarbons that are composed of carbon and hydrogen.
Source rocks are rocks that produce hydrocarbons from organic matter that are buried within the rock pore space.
Shale is the most common source rock for most oil and gas sedimentary rocks.

22. Continued Types of shale are Black, Green or Gray Shale
Black shale has about 1 – 3 % of organic matter. Green or Gray shale has about 0.5 % of organic matter.
Only about 2 % of deposited organic material becomes hydrocarbon. And only about 0.5 % is found in commercially exploitable reservoir.
Coal comes from woody plant remains deposit.
Low quality coal generated at lower temperature and pressure
High quality black coal is buried deeper under higher temperature.
Methane (Hydrocarbon gas) is also generated as a bye product from woody plants remains when coal is formed. This can migrate upwards to form a Gas Reservoir.

23. Vital Rock Properties
Hydrocarbon is formed in pore spaces of a source rock.
Rocks can be:
1. Highly or well consolidated
2. Poorly consolidated or unconsolidated
This is controlled by the mineral bonding holding the rocks together.
Which of the two above will have a stronger bonding?
Two Important rock properties are Porosity and Permeability.
1. Porosity – the extent of porosity is measured as the fraction of the total rock volume occupied by the pore spaces. Porosity is expresses in percentage
- Rock porosity is very important because without porosity hydrocarbon cannot be generated, migrate or accumulate in a reservoir.

24. Continued
If 30 % of the total volume of a rock has pore spaces , what is the rock porosity?
2. Permeability – Ability of a rock to allow fluid to flow through it. It is measured in darcies.
- Needs connected pore spaces.
- Rock permeability is very important because oil generated in the source rock cannot migrate into a reservoir.
Shale has very low porosity and low permeability.
Hydrocarbon and water produced in the shale source rock are squeezed out by pressure and it takes a longtime for the fluids to migrate out.

25. Primary Migration
The first two conditions necessary for the birth of a reservoir are :
1. Organic rich source rock.
2. Temperature and time for hydrocarbon generation.
Finally, the source rock should be next to a permeable rock or channel that allows for hydrocarbon migration.
-Conduit of hydrocarbon can be provided by permeable sandstones, fractures in the rock or ancient reefs.

26. Structural Traps
A structural trap has the ability to trap the hydrocarbon as a result of it’s primary migration from a source rock.
Maybe formed in a deformed rock as a result of movements within the earth crust.
Examples of structural traps are:
Anticline
Salt Dome
Angular Unconformity

27. Reservoir Rock
Hydrocarbon (gas or oil) and water are found in pore spaces or fractures within the rock matrix.
Most reservoirs are sandstones which have good porosity to hold hydrocarbon and high enough permeability for production.
Carbonates (limestone) with fractures and/or pit tend to be prolific reservoirs with high porosity and permeability.
Reservoir rocks that have clay within the pore spaces tend to reduce permeability around the wellbore.
Reservoirs may have different layers of varying characteristics that leads to what is known as directional permeability….difference in permeability due to direction of hydrocarbon flow.

28. Seal Rock
Impermeable rock that is a seal above a reservoir rock to prevent upward migration of hydrocarbon.
Clean shale, salt and unfractured limestone are examples of seals.
Seal rocks are a source of a formation pressure transition from a normal pressure to overpressure.

29. Secondary Migration
Formation of hydrocarbon pools due to movement of hydrocarbon droplets within the reservoir.
Also another step may occur when the earth crust movement shifts the pools position within the reservoir rock.
Accumulations can be affected by:
Buoyancy
Other Impermeable barriers
Hydrocarbon accumulations in carbonate reservoirs
Different layers of shale in large sandstone may distribute reserve with earth crust movement.

30. Continued 5. Faults 6. Uplift and erosion 7. Cap rock fracturing
Single Phase Reservoirs – contain only single fluid (gas or oil). Oil is seldom found without some gas or some water.
Most Reservoirs are multi-phase – they contain mixtures of gas, oil, and water
Secondary migration separate’s this fluid out by gravity, and gas sits at the top (Gas Cap), and then oil under gas and water under oil (lightest fluid at the top of heaviest fluids at the bottom)

31. Reservoir Drives
Energy that is used to move the hydrocarbons to the surface from the reservoir when first drilled.
Most oil when first drilled have sufficient pressure (energy) in the reservoir to push the oil to the surface.
Types of energy sources:
1. Gas Drive – partially or completely isolated from the pressure regime in the surrounding rock. Oil production causes the gas cap to expand and looses it energy.
- The temperature and pressure in the reservoir will drop and there will not be enough energy left to drive the oil out of the reservoir.

32. Continued Gas drive is not an efficient long-term production producer.
The following can be done if there is no sufficient pressure left to drive out oil in order to increase the reservoir pressure:
Inject more gas
Ignite oil underground by injecting air
Install a down hole pump to pump oil to the surface

33. Continued 4. Inject gas into the well (gas lift)
5. Inject water and chemicals in some part of the reservoir
All of the above method are called secondary recovery method.
Water Drive – has a reservoir that is connected hydraulically to an area regime (i.e such as aquifer that is open to the atmosphere).
- In addition, in a sedimentary rock sequence, there is a local water table(rock pore spaces with salt water, which exerts a pressure at depth. (Principles of hydrostatic pressure)

34. Continued
- The water from the local water table pushes the oil to the oil well.
- Water drive last longer than gas drive.
- water is eventually produced as oil is driven out from the well and may cause what is known as water blocking in the well (Increase in the amount of water in the pore spaces blocks oil)

35. Problems Related to fluids in the reservoir
Hydrogen sulfide can be produced from degradation by bacteria of the oil in a reservoir
- it is extremely toxic and it is also called sour gas.
Carbon dioxide in reservoirs can lead to corrosion of steel in a wet environment.
- This can cause corrosion problems for well tubular.
Hydrocarbons that have both H2S and CO2 are normally treated before they are sold.

36. Drilling a Land Exploration Well
Overview – This will cover the planning and execution of exploration well drilling on land .

37. Identifying a Prospect
An area called a Block is purchased by an oil and gas company to explore for hydrocarbon.
A permit is bought to explore on the block by the operator because they believe:
1. The geology shows indication of hydrocarbon accumulation
Cost of exploration will be worth the chance of finding an exploitable well
They can afford to absorb the exploration cost if nothing substantial is found or can afford to develop any discovery to produce hydrocarbon to market.

38. Continued An exploration well is drilled to gain information.
It is false economy to drill an exploration well to later produce hydrocarbon. This is due to the lack of sufficient information about a reservoir rock when a well is first drilled as an exploratory well that may affect the well design of a producing well, if unexpected changes conditions are encountered while drilling.
Exploration wells should be minimum cost well that should be used to get essential information and then abandoned.

39. Well Proposal
Let us a use an example of a potential trap of oil and gas in an angular unconformity structure. There are indications that it contains a gas cap on top, with a column of oil and water below. A call was made to drill the well into the edge of the gas cap and follow the bedding plane down through the oil and into the water.
The above is done in other to establish the following well objective:

40. Continued
1. Prove that oil and gas both exist in the reservoir, samples of each are collected for analysis, and the fluid pressures are measured in the reservoir. 2. Determine the gas-oil and oil-water contact depths. 3. Take rock samples in the oil part of the reservoir. 4. Test the oil layer to measure the following: a. The maximum rate at which the oil can flow before the start of sand production. b. The maximum possible production rate. c. Internal reservoir characteristics of the reservoir such as: permeability, porosity, internal pressure, and temperature.

41. Continued
d. Indications of damage to the reservoir from the drilling operation. This is known as mechanical skin and causes permeability reduction. After the well objectives are carried out from the exploratory well, a well proposal is written, which is request from the exploration department for a well to be drilled. It provides the necessary information to the drilling department to start designing the exploratory well.

42. Continued
The Well Proposal Content: The well proposal contains the following information:
1. The type of well (exploration) and well objectives (as stated above)
2. Essential well design data:
a. Surface (rig) location to use, if known.
b. Down-hole targets to hit along side acceptable margin for error.
c. Description and depth of the down-hole rock strata as far as possible.
d. Expected down-hole formation strengths and fluid pressures inside the rocks.

43. Continued
e. The down-hole temperature variation with depth. (Temperature profile)
f. What information is required from the well.
g. If core samples of rock will be obtained and at what depths.
h. If the well should be abandoned or temporary secured for later use after operations
The well completion design.
The drilling department will have to review the well proposal to make sure the following criteria are met:

44. Continued The proposal is logical, and the objectives can be achieved.
The essential well design data is complete , and there are no ambiguities or omissions.
The directional target for the well hits the reservoir as large as possible. This is in other to reduce the well cost if a smaller target is hit.
The proposal does not give rise to unsafe hazards to personnel , rig or well.
After the well proposal is agreed to by all parties, the drilling engineers start the well design.

45. Well Design and Drilling Program
A well design defines the final status of the well.
A drilling program is a document that the drilling engineers use to advise the rig on how the well design might be achieved.
- A drilling program can be modified due to unplanned events during drilling.
Well Design
There are five areas that must be defined when designing a well:

46. Continued
Completion design - this is conduit design for hydrocarbon to travel from the well bottom through the well head and to the surface production facilities.
Casing design - it defines the pipes and cement sheath that seals the space between the casing and hole.
Directional profile - The 3D path of the well from the surface location to the reservoir.
Wellhead configuration - it is a surface pressure tight component assembly that handles the load imposed on the well, such as casing string weight and internal fluid pressure from the well.

47. Continued
Well Fluids requirements - the final fluid mixture configuration after drilling.
Completion: consists of many pieces of tubing that are joined together.
- All the joined tubes are called a string
- A connection is what makes up’s series of tubing’s and also casings.
- Completion connections has to withstand both the tubing weight plus additional weight and allow hydrocarbon flow without leaks.
- There are other components such as Valves that control fluid flow and components to position other tools inside the tubing

48. Continued
- Parkers can also be used to form a seal between the outside of the completion tubing and inside of the casing. Normally, Parkers are used to prevent the flow of hydrocarbons outside the tubing. (diag)
One device that is installed in every completion is a subsurface safety valve (SSSV). It a can be placed surface (or below the seabed). This used for well control.
The completion in an exploratory well is a simple configuration used to test well performance with a production test or well test. The type of completion is called test string.

49. Continued
Casing Design - designed from the bottom up starting from the total well depth.
- Normally determined by the completion design. This is also related to the hole size and casing size.
The fluid pressure at the well bottom and rock strength higher up are used to help select the next casing point depth which is cemented in place.
Depth sand size’s of all casings are designed by the drilling engineer.
Casings and their connections must withstand the forces imposed by the casing weight, lowering the casing down-hole (bending due to well path), internal pressures and high temperatures.

50. Continued
Directional Profile: Wells can be drilled vertically or directionally depending on the well objective.
- Directional wells can be a low or high angle build or drop well or Horizontal well.
- Directional wells are drilled to: intersect a target that cannot reached when drilled vertically, to drill two or more wells from a single pad, for precise placement in a small reservoir target for maximum production and intersect multiple reservoirs in well path.
mention types of casing with directional profile (diag)
A relief well can be a vertical or directional well which is drilled to help relief an adjacent well with over flowing hydrocarbons.

51. Continued
There are two types of depth 1) Measured depth and True vertical
depth.
Wellhead – visible part of the well. The three main types of wellheads are:
1. Land wellhead – used with a beam. No pressure on wellhead. Oil pumped to surface with a pump. No parker between the completion and casing.
2. Subsea wellhead – placed on the sea-beds. It has a housing on top with running tools that is visible to lower the wellhead and release it.
3. Spool type wellhead – consist of a conductor casing at the bottom, then a surface casing is hang with a casing hanger inside that sits on top of the conductor casing. An intermediate casing is ran Inside the surface casing and sits in the casing head housing and it is secured with it’s own casing hunger. A production casing can also be run from the surface.

52. Continued
Well Fluids: After drilling, the fluid types to be left inside will be specified before a completion fluid or parker fluid (brine) before a completion tubing is run.
Drilling Program
- it contains advisory instruction to the well on how a well should be drilled.
- it is an advice that can be subject to change if necessary.
The following can be major headings of a well program for drilling and completing a well:
1. General Information
2. Well Objective
3. Potential Hazards
4. Surface location and how the rig is to be positioned

53. Continued
5. General notes, including: a. Reference to government regulations, company polices, and oilfield standards. b. Reporting procedure c. Quality control and data recording requirements. d. A diagram of the completed well. e. Equipment checklist and suppliers of each item. f. Cost estimating information to allow the well cost to be calculated . 6. Drilling notes fro each hole section , that includes the following:

54. Continued
A potential hazard or problems, how to avoid them, and how to recover.
Required drilling practices
Recommended operational sequence of events.
Kick tolerance
Drill bits recommended
Bottom assembly recommended
Any special requirements

55. Continued
7. Drilling fluid design and maintenance requirements for the whole well
8. Wellbore trajectory information
Casing design for the well and how they should be cemented.
Geological information of the formations to be penetrated.
Logging and coring programs.
12. Well completion design.
13. Well test information (if it will be production tested)
14. Well status when rig has finished work.

56. Drilling a Well
General sequence is similar for almost all well drilled.
Location preparation and conductor driving:
- Obstructions are cleared and removed.
- a hole is dug on under the rig on land so that a Blow out preventer can be placed on top of the casing.
Ordering Equipment:
- Quality control is important on equipment ordered. Must meet industry standard
- Give time to get equipment.

57. Continued Checking the infrastructure:
- Drilling operations should be able to handle high volume traffic at anytime of the day or night.
Moving the rig on location and attaching a diverter:
- Land rig break down into packages that are moved by a truck. Each major part must be accurately positioned relative to the substructure.

58. Continued Spudding the well:
After the conductor pipe is driven into the ground and the debris is then circulated with mud.
- The first drill bit drills a hole called the Pilot Hole (because the hole will be redrilled later) with a larger bit. The start of drilling this hole is called spudding the well. This time is taken as to when the drill bit leaves the bottom of the conductor pipe.
- Spud mud is the fluid used to drill the top section of the mud.
Discuss drill bits, drill collars, mud , flow-rate,
operating parameters and limitations in spuddng a well.

59. Continued Drilling the first hole section:
- A well is drilled until it reaches the depth to run the surface casing.
- one common problem with drilling surface hole section is lost circulation (fractures or permeable rock)
- Discuss Drill-pipe’s and tool joint, drill collar, x-over sub, bit sub, what is BHA et.c
- When drilling is stopped, the hole is circulated with mud to remove all cuttings before the pulling out. If not…mention what can happen. This circulation is called circulating clean.

60. Continued
- Caving is described as a result of rock falling of the side of the wall when drilling surface holes that have weak and unconsolidated formations. - Three 30 ft pipe screwed together is called a stand (90 ft). - The pilot hole size is enlarged with a Hole Opener (has a bull nose on the bottom) to be able to run the surface casing.

61. Continued Running and Cementing surface casing:
- Surface casing is cemented in place with the casing shoe in the strong formation.
- The CHH is used to hold the surface casing on top above the conductor pipe and it is attached on top to the Blow Out Preventer (BOP).
- BOP and control systems must be pressure tested.
- BOP systems come in pressure rating of 2000 psi, 3000 psi, 5000 psi, 10,000 psi and 15,000 psi. BOP also come in different sizes and the size is the nominal inside diameter of the BOP.

62. Continued Drilling out the casing and testing the formation strength:
- A float shoe (valve made up of cement with some plastic components) is below the surface casing.
- This is drilled out with cement below to do a formation strength test below the casing shoe.
- Drill bit is pulled into the casing and the blow out preventer is closed to provide a seal. Fluid is pumped slowly into the drillpipe.
- After a while the volume of fluid pumped would result to higher surface pressure from normal and this point is called Leak-off test.

63. Continued
When you know the depth of the formation and The pressure it will bear the formation strength gradient can be calculated: i.e. : 730 psi total pressure on formation divided by depth = formation strength gradient - The driller can figure out the maximum surface pressure that can be exerted on the well with the particular drilling mud density in the hole. This is called the Maximum allowable annular surface pressure (MAASP) and can be calculated by:

64. Continued
MAASP = (Formation strength gradient – Mud gradient) * Vertical Depth I.e. with 0.5 psi/ft mud in the hole MAASP is 230 psi. So a reduction in mud gradient is equal to reduced MAASP. So, if the MAASP pressure is exerted in an overpressure formation, then a Kick is likely to occur.

65. Continued Drilling the intermediate section:
- Normally drilled to a given direction and target that is not the surface location.
- A BHA is made up to build or drop or hold in this section.
- A will may contain more than one intermediate casing or non, if it is a shallow well.

66. Continued
Logging:
Usually ran as a wireline tool in the intermediate hole section for the following reasons:
To establish formation tops and thickness.
Litho logy, porosity, pore fluid sanity, and presence of hydrocarbons.
Continuous hole profile
Formation compressive strength.

67. Continued Running and cementing the first intermediate casing:
- As with the surface casing a float shoe is screwed on the bottom, then after two joints of casing, a float collar is run. Float collar is different from a float show because it has thread at the bottom and allows other casing to be run inside it.
The casing head housing and hoses are made up to the casing. Hoses are for fluid conduit.

68. Continued
- Pressure testing is done above the casing hanger to ensure that the hanger seal works, then the BOP can be removed.
- Afterwards, a housing called the casing spool as added to the wellhead. This is made up of casings, hanger and spools.
The next BOP which is smaller than the first is attached to the top of the spool. It has a higher pressure rating

69. Continued Drilling the production hole section:
- Casing normally set above the reservoir and the reservoir is drilled through to set a liner.
- liners are not ran to the surface, but suspended with a liner hanger inside the ID of the last casing
- advantages of liners are: reduced cost (short length of casing pipe and less cement needed) and a disadvantage is increased difficulty running it downhole
- it is essential to run cores into the reservoir to get information while drilling through the reservoir. -
Logging the hole: tools ran to provide well information
-Takes sample of the formation fluids, pressure readings and measure formation permeability
Running and cementing the production liner:
- Drillpipe use to lower the liner with the Liner hanger can be mechanically or hydraulically set inside the casing ID
- Cement is placed in the annulus and drillpipe is released from the liner hanger and pulled out.

70. Production Testing the Well
The cutting samples, logs and core samples show there is hydrocarbon
Preparing the well for the test string:
- it involves cleaning the hole section with fluid
Running the test string:
- A string of tubing that is run fro hydrocarbon production for production testing (drill stem test)
- it has s SSSV for well control.
Tubing is suspended at the well head
The BOP is removed and a Christmas tree is installed

71. Continued
- A special BOP is placed on top of the Christmas tree, which allows well’s to be perforated with wire-line while providing a seal.
Perforating the Well:
- A logging cable is used to run perforating guns inside the tubing to perforate the tubing opposite the reservoir.
Testing the well: discussed later
Killing the well after the production test is complete:
- Heavy fluid is pumped to kill the well, once the well test is over.

72. Abandoning the well
A well is abandoned when there is use for it after well testing. This is done by placing cement in the well.
Removing the test string:
- Test string is pulled out once the well is dead.
Making the well safe into the future:
- Cement is pumped into the perforations
- casing is cut and pulled out
- Conductor is cut and cement is dumped on top.