Amount of cuttings produced per foot of hole drilled
Annular Pressure Loss
Annular-Capacity
Annular-velocity
Bulk Density Calculation
Buoyancy Factor Oilfield
Convert Pressure to Equivalent Mud Weight
Convert-Specific-Gravity
Cost Per Foot Calculation
Critical RPM
D Exponent Calculation
D Exponent Corrected Calculation
Decrease Oil Water Ratio
Density of Oil Water Mixture
Depth of Washout
Dilution LGS control
Dilution LGS control – adding mud
Directional Survey Calculation – Angle Averaging Method
Directional Survey Calculation – Radius of Curvature Method
Dogleg Severity Calculation – Radius of Curvature Method
Dogleg Severity Calculation – Tangential Method
Drilling or Connection Ton-Mile
Drill-pipe-pulled-to-lose-certain-hydrostatic-pressure
Equivalent Circulating Density Calculation
Equivalent Circulating Density with engineering formula
Formation Integrity Test
Formation Temperature
Free Point Constant Calculation
Hydraulic Horse Power
Hydrostatic Pressure Calculation
Hydrostatic Pressure Decreases When POOH
Increase mud weight adding Barite
Increase mud weight adding calcium carbonate
Increase mud weight adding hematite
Increase Oil Water Ratio
Internal Capacity
Lag Time Calculation
Leak off test calculation
Light Weight Spot Pill
Loss hydrostatic due to filling water into annulus
Mix Different Fluid Density – Limit Space
Mix Different Fluid Density – Unlimit Space
Mud Volume Increase Due to Adding Barite
Mud Volume Increase Due to Adding Calcium Carbonate
Mud Volume Increase Due to Adding Hematite
Oil Water Ratio from a Retort Analysis
Pipe Displacement Calculation
Pressure and Force Calculation
Pressure Gradient Calculation
Pressure Required to Break Circulation In Annulus
Pressure Required to Break Circulation Inside Drill String
Pump Output (Duplex and Triplex)
Pump Pressure and Pump Stroke Relationship
Reduce Mud Weight by Dilution
Slug Calculation – Barrel of Slug Required
Slug Calculation – barrels of slug required for a desired length of dry pipe
Slug Calculation – Weight of Slug Required
Specific Gravity Calculation
Starting Volume for Weighting Up with Bartie
Starting Volume for Weighting Up with calcium carbonate
Starting Volume for Weighting Up with Hematite
Stuck Pipe Calculation – Not Know Free Point Constant
Stuck Pipe Calculation – Use Table for Free Point Constant
Temperature Conversion Formulas
Ton-Mile (TM) for Coring Operation
Ton-Mile (TM) for Making Short Trip
Ton-Mile (TM) for Round Trip
Ton-Mile (TM) for Setting Casing
Ton-Mile (TM) for Drilling or Connection

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

Formula, used to calculate dilution of mud system, is listed below;

Vwm = Vm x (Fct – Fcop) ÷ (Fcop – Fca)

Where; Vwm = barrels of dilution water or base fluid

Vm = total barrels of mud in circulating system

Fct = percent low gravity solids in system

Fcop = percent total low gravity solids desired

Fca = percent low gravity solids bentonite and/or chemicals added in mud

Example: Determine how much barrels of oil base mud to diluate total 2000 bbl of mud in system from total LGS = 7 % to desired LGS of 3.5 %. The oil base mud has 2% of bentonite slurry.

Vwm = Vm x (Fct – Fcop) ÷ (Fcop – Fca)

Vwm = 2000 x (7 – 3.5) ÷ (3.5-2)

Vwm = 4667 bbl

In order to dilute total of 2000 bbl of the original mud with 7% LGS down to 3.5% LGS, 4667 bbl of mud that has 2% bentonite is requied to add into the system.

Please find the excel sheet used to calculate how much barrel of drilling fluid to control Low Gravity Solid (LGS) in mud system.

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

Formula used to calculate dilution of mud system is listed below;

Vwm = Vm x (Fct – Fcop) ÷ (Fcop)

Where; Vwm = barrels of dilution water or base fluid needed

Vm = total barrels of mud in circulating system

Fct = percent low gravity solids in system

Fcop = percent total low gravity solids desired

Example: Determin how much barrels of base oil to diluate total 2000 bbl of mud in system from total LGS = 7 % to desired LGS of 3.5 %.

Vm = 200 bbl

Fct = 7%

Fcop = 3.5%

Vwm = 2000 x (7 – 3.5) ÷ 3.5

Vwm = 2000 bbl

In order to dilute total of 2000 bbl of the original mud with 7% LGS down to 3.5% LGS, 2000 bbl of base oil is requied to add into the system.

Please find the excel sheet used to calculate how much barrel of base fluid to control Low Gravity Solid (LGS) in mud system.

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

How can we decrease oil water ratio to 70/30?

Let’s make it simple so I still use the same information as my previous post. We start with 100 bbl of mud and we have the following information from the retort analysis.

Retort analysis:

% by volume oil = 56

% by volume water = 14

% by volume solids = 30

According to this retort analysis, the oil water ratio is 80/20 (learn how to calculate oil water ratio from a retort analysis) and there are 56 bbl of oil, 14 bbl of water and 30 bbl of solid from 100 bbl of mud.

In order to decrease oil water ratio, water must be added but oil volume remains the same. Therefore, 56 bbl of oil will represent 70% of oil ratio for the new system. We give X equals to the new total liquid volume (combination of oil and water volume).

Then; 70 = (56×100) ÷X

X = 80.0 bbl

Total liquid volume is equal to 80.0 bbl.

Oil volume is still the same but water volume will be added into the system. With this concept, the volume of water will added into the system can be described with the following relationship;

Water added = new total liquid volume – original volume

Water added = 80 – 70 = 10 bbl

If you have the total mud volume of 300 bbl, you will need 30 bbl of water added (10 x 300 ÷ 100) in order to decrease oil water ratio from 80/20 to 70/30

Please find the Excel sheet used for decreasing oil water ratio.

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

How can we increase oil water ratio from 80/20 to 85/15?

Let’s make it simple to understand. We start with 100 bbl of mud and we have the following information from the retort analysis.

Retort analysis:

% by volume oil = 56

% by volume water = 14

% by volume solids = 30

According to this retort analysis (learn how to calculate oil water ratio), the oil water ratio is 80/20 and there are 56 bbl of oil, 14 bbl of water and 30 bbl of solid from 100 bbl of mud. In order to increase oil water ratio, oil must be added and water volume remains the same. Therefore, 14 bbl of water will represent only 15% of water ratio for the new system. We give X equals to the new total liquid volume.

Then; 15 = (14×100)÷X

X = 93.33 bbl

Total new liquid volume is 93.33 bbl

Barrel of base oil added per 100 bbl of mud

Oil added = new total liquid volume – original volume

Oil added = 93.33 – 70 = 23.33 bbl

It means that you need to add oil 23.33 bbl per 100 bbl of original mud without adding any volume of water in order to achieve 85/15 oil water ratio.

Please find the Excel sheet for calculating how to increase oil water  ratio.

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

The formulas below demonstrate how to calculate oil water ratio from retort data.

a) % oil in liquid phase = (% by volume oil x 100) ÷ (% by volume oil + % by volume water)

b) % water in liquid phase = (% by volume water x 100) ÷ (% by volume oil + % by volume water)

c) Result: The oil/water ratio equals to the percent oil in liquid phase and the percent water in liquid phase.

Example: Determine oil water ratio from following information

Data from a retort analysis:

% by volume oil = 56

% by volume water = 14

% by volume solids = 30

Solution:

a) % oil in liquid phase = (56 x 100) ÷ (56+14)

% oil in liquid phase = 80

b) % water in liquid phase = (14 x 100) ÷ (56+14)

% water in liquid phase = 20

c) According to this retort report, the oil/water ratio equals to 80/20.

Please find the excel sheet used for calculating oil water ratio from retort data.

Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition

(V1)(D1) + (V2)(D2) = (V1 + V2)DF

Where;

V1 = percentage of oil

V2 = percentage of water

D1 = density of oil

D2 = density of water

DF = final density of mixed fluid between oil and water

Example: If the oil/water (o/w) ratio is 80/20 (80% oil and 20% water), please determine the density of mixed fluid between oil and water from the retort. Oil density = 7.0 ppg. Water density = 8.33 ppg.

V1 = 0.8

V2 = 0.2

D1 = 7.0

D2 = 8.33

(V1)(D1) + (V2)(D2) = (V1 + V2)DF

(0.8)(7.0) + (0.2)(8.33) = (0.8 + 0.2) DF

5.60 + 1.67= 1.0 DF

7.27 = DF

The density of the oil/water mixture = 7.27 ppg

Please the Excel sheet used to calculate the density of oil and water mixture.

Ref: Formulas and Calculations for Drilling, Production and Workover, Second Edition