As per previous topic, driller’s method well control, it stated about overall of driller method and this post will show the detailed of driller’s method and describe in term of operation stand point as well. I separates all detailed-step of driller method into several blog post because I want to add a lot of details for each topic so you will clearly understand about driller method and you also can apply with your real life operation.

Today I will start with the first one is to shut in well and obtain pressure information

1. Shut in the well and get pressure data

After the well is shut-in with proper shut in procedures (read more about shut in procedures), personnel must take few minutes until the shut-in pressure to stabilize. Both the drill pipe and the casing gauge will dictate if the well stabilizes. While waiting for the well to stabilize, crew can have a chance to check everything is ready for killing operation as well.

After the well stabilizes, you will know how much shut in casing pressure (SICP) and shut in drillpipe pressure (SIDPP). However, if your BHA has a float inside, you will not see the SIDPP yet hence you must bump the float in order to get the SIDPP.

You may need to review the float bumping procedure to obtain shut-in drill pipe pressure.

After passing these steps above, you get the SIDPP and SICP.

Ref books: Well Control Books

In order to get the correct value of drill pipe pressure, you need to have the correct floating bumping procedure. In this section, I will show you how to bump the float correctly.

These following procedures will demonstrate you how to bump the float correctly in order to get SDPP.

1. Ensure well is properly shut in. No leak or whatever.

2. Record shut in casing pressure (SICP)

3. Pump as slowly as possible (5-10 stroke per minute) at constant pumping speed down into the drill pipe and keep monitoring the drill pipe pressure and the casing pressure.

4. You will see the drill pipe pressure increase while pumping. At this stage, you need to monitor carefully for a “lull” in the drillpipe pressure, which will occur when the float is opened. The drillpipe pressure showing when the lull is first seen is your shut in drill pipe pressure (SIDPP).

5. You also need to verify that the float has been opened by continuing to pump down the drillpipe slowly until you see an increase in the casing pressure. It should happen very quickly after the lull was seen on the drillpipe gauge.

6. Shut down the pumping operation as soon as increase in casing pressure is detected.

7. Check the shut-in casing pressure again. If there is any excess casing pressure, you may bled-off some pressure in small increments until it equates or a little bit above SCP in steps no 2.

If you see trapped pressure on drill pipe after bumping the float, you can calculate the actual shut in drill pipe pressure with this following formula.

Shut in drill pipe pressure = shut in drill pipe pressure after bumping the float – Shut in casing pressure increase while bumping float

Ref books: Well Control Books

The tangential method is the simplest calculation among other directional survey calculations.

The tangential method formulas are listed below;

Tangential Method Calculation formula

Where;

MD = Measured Depth between surveys in ft

I1 = Inclination (angle) of upper survey in degrees

I2 = Inclination (angle) of lower in degrees

Az1= Azimuth direction of upper survey

Az2 = Azimuth direction of lower survey

The following example is the Tangential Method Calculation.

Survey 1

Depth = 3500 ft

Inclination = 15 degree (I1)

Azimuth = 20 degree (Az1)

Survey 2

Depth = 3600 ft

Inclination = 25 degree (I2)

Azimuth = 45 degree (Az2)

Solution:

MD = 3600 – 3500 = 100 ft

As per the formulas above, you will get answers as listed below;

North = 29.88 ft

East = 29.88 ft

TVD = 90.63 ft

Please find the Excel sheet used for The Tangential Method Calculation

Ref books: Directional Drilling Books

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

The Minimum Curvature Method smooths two straight-line segments of the Balanced Tangential Method by using the Ratio Factor (RF).

The formulas for the Minimum Curvature Method are listed below;

β must be in radians

Where;
MD = Measured Depth between surveys in ft
I1 = Inclination (angle) of upper survey in degrees
I2 = Inclination (angle) of lower in degrees
Az1= Azimuth direction of upper survey
Az2 = Azimuth direction of lower survey
RF = Ratio Factor
Β is the dog leg angle.

The following example is the Minimum Curvature Method Calculation

Survey 1
Depth = 3500 ft
Inclination = 15 degree (I1)
Azimuth = 20degree (Az1)

Survey 2
Depth = 3600 ft
Inclination = 25 degree (I2)
Azimuth = 45 degree (Az2)

Solution:
MD = 3600 – 3500 = 100 ft

β = 0.22605 radian = 12.95 degree

RF= 1.00408

As per the formulas above, you will get answers as listed below;

North = 27.22 ft
East = 19.45 ft
TVD = 94.01 ft

Please find the Excel sheet used for The Minimum Curvature Method Calculation

Ref books: Directional Drilling Books

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

I have some directional calculations that I’ve shared with you. However, some of them are not shared yet so I will try to share all directional drilling formulas that may be helpful for you in the future.

Today, I would like to show you about Balanced Tangential Method Calculation. This calculation method treats half of the measured distance (MD/2) as being tangent to I1 and Az1 and the remainder of the measured distance (MD/2) as being tangent to I2 and Az2.

The formulas for the balanced tangential method are listed below;

Where;

MD = Measured Depth between surveys in ft

I1 = Inclination (angle) of upper survey in degrees

I2 = Inclination (angle) of lower in degrees

Az1= Azimuth direction of upper survey

Az2 = Azimuth direction of lower survey

The following example is the Balanced Tangential Method Calculation.

Survey 1

Depth = 3500 ft

Inclination = 15 degree (I1)

Azimuth = 20degree (Az1)

Survey 2

Depth = 3600 ft

Inclination = 25 degree (I2)

Azimuth = 45 degree (Az2)

Solution:

MD = 3600 – 3500 = 100 ft

As per the formulas above, you will get answers as listed below;

North = 27.1 ft

East = 19.37 ft

TVD = 93.61 ft

Please find the Excel sheet used for The Balanced Tangential Method Calculation

Ref books: Directional Drilling Books

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

Drilling personnel need to fully understand about the lag time. Lag time is time delay from pressure adjustment made on a choke valve or a choke HCR to show up on the drill pipe pressure gauge.

Does it sound confuse? Let’s me explain more about it. When you adjust a choke position, you will not be able to see changes on the drill pipe gauge right away because drilling fluid is compressible so you need to be patient and wait a little bit until you see the changes on the drill pipe gauge.

How can we know how many seconds for the lag time?

We can roughly estimate the lag time about 2 seconds per 1,000 MD. This number is just a rule of thumb. If you want the actual lag time, you can determine it by performing a choke drill. You really need to know about the lag time otherwise you can get confused a lot when you attempt to adjust drill pipe pressure.

Ref books: Well Control Books

Driller’s method is one of several methods to kill the well in well control operation. The main idea of driller method is to kill the well with constant bottom hole pressure. The Driller’s Method of well control requires two complete and separate circulations of drilling fluid in the well.

The first circulation removes influx with original mud weight. When starting to bring pumps up to speed, casing pressure must be held constant until kill rate is reached. Then drillpipe pressure is held constant to maintain constant bottomhole pressure which is normally equal to, or slightly greater than pore pressure. Drillpipe pressure will be held constant until influx is removed from annulus. If the wellbore influx is gas, it will expand when it comes close to surface therefore you will see an increase in pit volume and casing pressure.

After the kick is totally removed from the well, when the well is shut-in, drillpipe and casing pressure will be the same value. If not, it means that there is influx still left in the wellbore or trapped pressure.

Before going to the second circulation, we need to know kill mud weight which can be calculated from initial shut-in drillpipe pressure. The calculation part will be discussed as in next section.

Second circulation kills well with kill mud. When the required kill mud weight is mixed, it is the time to start the second circulation of driller method. We start with bringing pumps to kill rate by holding casing pressure constant. While circulating with the kill mud, casing pressure must be held constant until kill mud reaches the bit. After that, we need to hold drill pipe pressure constant then continue circulating with constant drill pipe pressure until kill mud weight reaches at surface. Then shut down pumping operation and observe drillpipe and casing pressure. If the well is successfully killed, both drillpipe and casing pressure will be zero. If not, there is some influx still in the well.

Ref books: Well Control Books

Shut-in procedures while wireline logging operation are very critical for all drillling crew working on the rig. Learn about two vital cases of the shut-in procedures.

Two cases of shut the well in while logging with wire line are as follows;

1. Shut the well in while wireline logging through open BOP without a lubricator.

2. Shut the well in while wireline logging through open BOP with a lubricator installed in the BOP.

Let’s talk about the first case: Shut the well in while wireline logging through open BOP without a lubricator.

First step: Stop logging operation

Second step: Shut the well in by following these procedures;

1. Close annular preventor because we would like to use the annular preventor element to squeeze around the wireline. You may need to increase closing pressure in order to have affective sealing ability if necessary.

2. Open a HCR valve against a fully closed choke manifold valve.

3. Use a trip tank to confirm that flow is stopped and the well is totally shut-in.

4. Inform drilling supervisors

The well sometimes cannot be totally shut in via a closed annular preventor therefore you must consider cutting the wireline and letting it drop then using blind rams to shut the well in instead. If the annular preventor could not seal around the wireline effectively and the wireline cannot be cut and dropped through the Blow Out Preventor (BOP), you may consider using shear rams to cut the wire as the last option.

Let’s talk about the second case: Shut the well in while wireline logging through open BOP with a lubricator installed in the BOP.

First step: Stop logging operation

Second step: Shut the well in by following these procedures;

1. Energize pack off seals at the lubricator. You may need to increase closing pressure in order to have affective sealing ability if necessary.

2. Open a HCR valve against a fully closed choke manifold valve.

3. Use a trip tank to confirm that flow is totally stopped and the well is properly shut-in.

4. Inform drilling supervisors

Ref books: Well Control Books

After you complete shut in procedure while tripping, there is following information that must be recorded before making any decision on how to kill the well.

Shut-In Casing Pressure (SICP): Read and record the shut-in casing pressure (casing gauge).

In order to get the proper pressure reading, the casing gauge should be installed upstream of the closed choke.

Pit Gain: Read and record the pit gain. Pit volume gained is very critical for the maximum casing pressure calculation.

Practically, while tripping out of hole, a trip tank is used to track displace volume in use. The accurate pit gain value can be easily figure out by finding difference between actual volume taken to fill up wellbore and theoretical fill up volume. However, if the active pits are used to record the displacement volume, it will be very difficult to figure out the accurate pit gain. The concept of determining the pit gain is the same as using the trip tank. However, the reason that I say that it is very difficult to get the accurate pit gain because pit volume is too large to record few changes while tripping.

Time: Record the time that the well control situation is occurred and keep an accurate time log for the entire well kill operation

Bit Depth: Record bit depth.

Ref books: Well Control Books

Tripping out of the hole is a critical operation, which drilling team must keep close eye on well control situation that can occur anytime. Wellbore monitoring and hole filling equipment and must be working properly so that the kick can be quickly detected. You must be aware of and prepared for the well control situation every tripping operation.

While tripping, it can cause swabbing effect that may allow formation fluid entering into wellbore. The well may not start to flow since the swabbing effect is just started. The swabbing effect will result in reducing the overall hydrostatic pressure. If the well is continually swabbed-in until the hydrostatic pressure in the wellbore less than formation pressure, the well will start flowing. Any time that you see short fill while tripping out, you need to go back to bottom and circulate bottom up to confirm wellbore condition.

When the well control situation is happened during tripping operation, the drilling crew must shut the well in right away using the following “3 S” shut-in procedures.

Stab Valve: Install Full-Open Safety Valve (FOSV) that must be in an open position in drill string. Make up to drilling string and close the safety valve.

Space Out: Space out to ensure that tool joint must no locate in BOP element.

Shut-in well: Close the annular preventer or uppermost pipe rams. Open the upper choke line valve against a fully closed manifold valve at a choke manifold. Line up to trip tank to confirm that the well is shut-in and flow has been stopped.

Ref books: Well Control Books