EXERCISE 7 Answer the following questions.

1. Where can you expect to find Н₂S?

2. What may happen if you enter a confined space?

3. May Н₂S be dissolved in liquids?

4. What should you do if you are near an oil and gas facility?

5. What may help to keep you out of danger if Н₂S is present?

6. Is Н₂S heavier or lighter than air?

EXERCISE 8 Describe which mistakes were made by personnel in the following situations.

TEXT 1

ACID TREATMENT

Dog house – балок, бытовка

An acid pumper arrives to a remote location to perform an acid wash and squeeze. The well is known to have a concentration of 20 000 ppm Н₂S. There is a service rig on location with a five man crew, an air trailer with a safety operator, one customer representative, one tank trunk operator, and a three man acidizing crew. The pumper is spotted upwind of the wellhead, 25 meters from the rig tank. A Kelly hose is run from the rig pump to the pumper unit. The pumper unit is rigged into a manifold to allow the pumping of fluid to either the tubing or casing.

The safety operator has a portable Н₂S monitor on site with sensors located at the rig tank and wellhead. There are SCBA units located in the safe area. The day before the alarms had sounded at the rig tank when the well was being circulated. The safety operator checks over the rig with a personal monitor before the safety meeting and finds no Н₂S. He feels there is no need to supply the pumper operator with a SABA and air hose.

During the safety meeting, the dangers of Н₂S are discussed and emergency procedures are reviewed. The pumper and rig pump operators get their units ready to transfer fluid from the rig tank. The rest of the personnel meet in the rig shack for coffee.

The rig pump operator starts to pump fluid from the rig tank to the pumper. The pumper operator looks in the tank to check the level and collapses on the far side of the truck. The rig pump operator does not see the operator fall and continues to pump. The supervisor comes out of the doghouse and sees his operator down and runs toward the pumper. The supervisor goes down as he reaches the unit. The rig pump operator sees the supervisor go down and stops pumping. The portable monitor at the wellhead then goes off.

TEXT 2

WELL SERVICE

A rig crew and air trailer attendant arrives to a location at the same time to start the day. The air trailer attendant unlocks the trailer and proceeds to stretch out the air lines. The rig crew goes into the doghouse to change their clothes.

One man, however, decides to check the shut-in tubing and casing pressure before changing his clothes. Once he records the pressure, he decides to bleed off pressure to an open tank. The return and kill lines had been drained the night before and not reconnected. The build-up pressure is released to the atmosphere. Approximately 2000 ppm of Н₂S is released to the atmosphere. It migrates downwind directly into the path of the air trailer attendant. He is instantly overcome and collapses near the end of the catwalk.

The second crewman sees the air trailer attendant slump to the ground. He rushes over to assist and is also knocked down. The first crewmember realizes what is happening and shuts the wellhead valve.

TEXT 3

DRILLING RIG

A rig crew was pulling a wet test. The crewmembers were all masked up. A safety supervisor, also masked up, was testing the floor area with a detector tube device. Several wet stands were pulled, and no Н₂S had been detected. The safety supervisor suggested the crew take off their masks, as they were tiring quickly. The situation was discussed with the rig manager and the well site representative. All agreed the crew should take off their masks. The safety supervisor would remain masked up and would continue testing.

The crew went back onto the floor without masks. A stand was pulled and the tool joint broken. The mudcan was put on, and the crew left the floor. The driller picked up on the stand and the mud drained. The safety supervisor opened the mudcan and tested. No Н₂S was detected. The crew was called back on the floor to hoist another stand. As they were about to hook on the elevators, a small mud burp was observed. The safety supervisor told the crew to leave the floor and he began to test.

Three of the crewmembers were going into the doghouse when the first one went down. Two more went down on top of him. The well was immediately shut in. The three crewmembers were revived shortly afterwards and taken to hospital. The safety supervisor detected 32% Н₂S.