Tag Archives: Well Control

Choke Line Friction – How Does It Affect Deepwater Well Control?

By | |
Leave a comment

Choke line friction (CLF) is the frictional pressure which is generated while circulating mud through choke or kill line. For surface stack, the choke line friction is negligible because the choke line is short therefore the friction pressure is so small. However, the choke line friction in deepwater operation has a big effect bottom hole pressure. Killing the well without considering the CLF will add excessive pressure and it increases the chance of fracturing formation at casing shoe or anywhere in the well.

choke-Line-Friction Continue reading →

Lost Circulation and Well Control

By | | ,
2 Comments

Lost circulation is a situation when drilling fluid losses downhole because formation(s) is fractured. There are three levels of lost circulation which are seepage loss, partial loss and total loss.

27-Lost-Circulation-and-Well-Control

Seepage loss is a situation when the mud volume loses into formation at very minimal and this will have no or little effect for a drilling operation.

Partial loss is a situation when some volume of drilling fluid loses into the well and you get some drilling mud volume back on surface. Not only do you lose the fluid volume, but you may have ballooning issue to deal. However, this type of fluid loss will not lead to well control situation because the total hydrostatic pressure does not decrease.

Total loss is the worst situation because there is no mud returning back to surface and the mud level will drop to any level down hole. Losing a lot of fluid into the well will directly affect hydrostatic pressure at the bottom. If you cannot keep the hole full, it might be a time when the hydrostatic pressure is less than the reservoir pressure. Eventually, a well control situation will be happened.

Additional information – What Cause Lost Circulation in Drilling Leading to a Well Control Situation

Continue reading →

Learn about Maximum Surface Pressure in Well Control (MASP, MISICP and MAASP)

By | |
2 Comments

There are several terms/acronyms about maximum surface pressure in well control such as MASP, MISICP and MAASP. These terms sometimes confuses a lot of people hence this article will explain each term and demonstrate how to use it.

26-MASP-MISICP-MAASP-cover

Leak Off Test (LOT)

The first factor you need to understand is Leak of test pressure (LOT). LOT is the surface pressure that breaks down formation at a casing shoe for each section of the well.

Leak off test pressure formula is listed below;

Leak off test pressure, psi = Surface pressure to break formation, psi + Hydrostatic pressure, psi

Typically, leak off test pressure is describe in equivalent mud density term therefore the formulas will be like this

Leak off test pressure, ppg = (Surface pressure to break formation, psi ÷ 0.052 ÷ shoe TVD, ft) + Mud weight, ppg Continue reading →

Trip Tank and Its Importance to Well Control

By | |
2 Comments

Trip tank is a small tank which has a capacity of 20 – 50 bbl and its shape is tall and shallow because it can effectively detect volume changes. The trip tank system has the ability to continuously fill the well and take return back to the tank. With this capability, it will keep the hole full all the time and the volume changes either increasing or decreasing can tell the condition of the well.

How The Trip Tank is Lined Up

The diagram (Figure 1) below demonstrates how the trip tank is lined up.

25 Trip Tank and Its Importance on Well Control 1

Figure 1 – Trip Tank Line Up To Continuously Fill The Hole

Continue reading →

Know about Swabbing and Well Control

By | |
2 Comments

There are several situations when a kick is induced by swabbing effect. Today, we are going to discuss swabbing and well control situation. Swabbing is a condition when the string is pulled out of the well and it creates temporary bottom hole pressure reduction. If the hydrostatic pressure reduction is large enough to create underbalance condition, the well will eventually flow.

24-Know-abou-Swabbing-and-Well-Control-cover

When you swab the fluid in, the swabbed fluid may not necessarily cause pit gain or the well flowing because the volume swabbed in is not significant. However, if you have several swabbed-in fluid, the well will finally flow.

Figure 1 - Take Swabbed Kick

Figure 1 – Take Swabbed Kick

It is quite tricky to recognize the swabbing volume and the most trustable method to detect is by tracking hole fill volume. For example, if the volume displacement for 10 stands pulled is 8 bbl but the hole fill volume is just only 6 bbl, 2 bbls of kick may possibly be swabbed in while tripping out. Once the swabbing is detected, you need to trip back to the bottom and circulate bottom up even though the well is not flowing. If you don’t go back to the bottom, it will be very difficult to control the well off bottom once the swabbed gas moves up to shallower depth of the well. Continue reading →