CHAPTER 2 (PART 2)

Question 1

SITUATION 1

Drill within the mud window between the formation pore pressure and the formation fracture because:

if BHP < F.P.P, then _____

Answer 1

formation fluid influx can occur

Question 2

According to SITUATION 1

How about if BHP > F.P.P, what will happen to the formation

Answer 2

formation will breakdown, mud losses can occur, primary well control barrier cannot be achieved

Question 3

What means BHP

Answer 3

Borehole Pressure

Question 4

A formation will fracture when ___

Answer 4

the pressure in the borehole exceeds the least of the stresses within the rock structure

Question 5

Fractures will propagate in a direction perpendicular to the ___

Answer 5

least principal stress

Question 6

To initiate wellbore wall fracture, the pressure in the borehole must be ___

Answer 6

greater than the least principal stress in the formation

Question 7

To propagate the fracture the pressure must be ___

Answer 7

maintained at a level greater than the least principal stress

Question 8

Drilling practice indicates that when the hydrostatic pressure of the drilling fluid is high enough, the ___

Answer 8

borehole wall will break

Question 9

The pressure of the drilling fluid column is defined as ___

Answer 9

formation fracture pressure

Question 10

What are some approaches to calculate fracture pressure based on empirical data analysis and numerical method?

Answer 10

• The Hubbert and Willis Method
• The Matthews and Kelly Method
• The Eaton Method
• The Rongzun Huang Method

Question 11

• A test that determines the fracture pressure of the casing shoe and open formation.

• It is conducted after drilling out of a new casing shoe to determine the maximum pressure that the open hole can withstand before the fluid in the wellbore will begin to leak off and fracture the formation.

• Traditionally, it is conducted to determine the upper threshold for the mud weight.

• It is used to determine the pressure at which the rock in the open hole section of the well just starts to break down.

Answer 11

Leak-Off Test

Question 12

The ___ is considered to be the first point that deviates from the usual pressure profile while pumping fluid down hole.

Answer 12

leak off pressure

Question 13

Installed between the pressure gauge and pump. Close this valve during shut-in; do not rely on the pump to hold pressure.

Answer 13

Shut-in valve

Question 14

Installed between shut in valve and pump. Open during shut in to check for leaks in the shut in valve. Also used to bleed off pressure when the test is completed.

Answer 14

Bleed valve

Question 15

Used to purge air. Open while filling drill pipe and test head, close when mud starts to flow out valve.

Answer 15

Purge valve

Question 16

Four inches or larger for easy visibility. Liquid filled, mounted away from test line for smoother readings. Lowest range, smallest dial increments possible to minimize uncertainties caused by needle oscillations.

Answer 16

Pressure gauge

Question 17

LOT operation is terminated when the ___

Answer 17

pressure no longer continues to increase linearly as the mud is pumped into the well

Question 18

When the pressure no longer increases linearly with an increase in volume pumped, it is assumed that ___

Answer 18

the formation is starting to breakdown

Question 19

•It is assumed in these tests that the weakest part of the wellbore is the formations which are exposed just below the casing shoe.

•when these tests are conducted, the pressure at surface, and throughout the wellbore, initially increases linearly with respect to pressure.

Answer 19

LOT and FBT

Question 20

what means ELOT or XLOT

Answer 20

Extended LEAK OFF TEST

Question 21

To identify the minimum horizontal stress 𝜎ℎ extended leak off test, ___ is introduced

Answer 21

(ELOT or XLOT)

Question 22

Slope of the straight line region gives the compressibility of the drilling fluid.

Answer 22

Extended LEAK OFF TEST (XLOT)

Question 23

what means FIT

Answer 23

FORMATION INTEGRITY TEST

Question 24

The purpose of conducting a FIT is to _____

Answer 24

test the formation fracture pressure required for kick tolerance and safe drilling mud weight margin

Question 25

The maximum pressure in the FIT test is _____

Answer 25

less than the fracture initiation pressure

Question 26

___ is used to determine whether the rock in the open hole section of the well will withstand a specific predetermined pressure. This pressure represents the maximum pressure that the formation will be exposed to while drilling the next wellbore section.

Answer 26

FIT

Question 27

The maximum allowable pressure on the formation just below the casing shoe is generally expressed as _____ so that it can be compared with the mud weight to be used in the subsequent hole section.

Answer 27

an equivalent mud gradient (EMG)

Question 28

In LOT calculations, a safety factor of _____ is subtracted from the allowable mudweight.

Answer 28

0.5 ppg (0.026 psi/ft)

Question 29

When the drilling fluid is circulating through the drillstring, the borehole pressure at the bottom of the annulus will be _____

Answer 29

greater than the hydrostatic pressure of the mud

Question 30

what means ECD

Answer 30

equivalent circulating density

Question 31

___ can then be calculated from the sum of the hydrostatic and frictional pressure divided by the true vertical depth of the well.

Answer 31

ECD

Question 32

LOT Calculations – MAASP

Answer 32

MAASP = Maximum Allowable Pressure at the Shoe MINUS Hydrostatic Pressure of Mud at the Shoe

Question 33

MAASP means

Answer 33

Maximum Allowable Annulus Surface Pressure