1. Part 2.2 Well Control

2. Objectives After reading the chapter and reviewing the materials presented the students will be able to: Understand well control Examine crewmembers role in controlling a well Discuss process of shutting in a well Analyze significance of wellbore pressure Describe early detection signs and warnings

3. Introduction A well is out of control when reservoir gas or fluids are flowing in a way that cannot be regulated or stopped. The most spectacular and hazardous blowout is a surface blowout when reservoir fluid escapes from a well at the surface. Surface blowouts can lead to massive environmental pollution, and cause injury or fatality to people nearby. Uncontrolled flows that occur within a well underground can also cause a downhole blowout. A downhole blowout wastes hydrocarbons by flowing them into other reservoirs where they can become unrecoverable.

4. First Line of Defense Crewmembers are the first line of defense against blowouts. Kicks and blowouts can be controlled by controlling wellbore conditions (pressure) at the first sign of danger. All blowouts occur through some form of human error.

5. Wellbore Pressure All well control problems are related to an imbalance of wellbore pressures. The drilling and production fluids act as a primary barrier during operations and hydrostatically balance the well. As the earth’s formation fluids enter the wellbore, drillers have to increase or decrease mud weight (density) to counteract such pressure. When positive fluid pressure is not properly controlled downhole, a kick will likely occur. If the kick is not brought under control quickly, a blowout will occur.

6. Shutting In a Well To shut in a well, crewmembers use blowout preventers (BOPs). A blowout preventer is a series of valves installed on the wellhead to prevent the escape of fluids from the casing and drill pipe. Several BOPs may be stacked on top of one another for maximum control. On floating offshore rigs BOPs are installed on the top of the wellhead on the ocean floor. When the drilling crew recognizes signs of a kick, the driller turns off the pumps, pulls the drill string off the bottom, and closes one or more of the BOPs. After all the reservoir fluids and old mud are replaced by circulating new heavier mud in the wellbore, the pressure in the well is once again higher than the reservoir pressure, and the reservoir fluid will no longer flow in the well. The BOPs can be opened, and drilling can safely resume. If a blowout occurs, then specialized firefighters are called in to handle the situation.

7. Early Warnings Eighty percent of all blowouts involve warning signs. Awareness and effective communication are the best defense. The industry spends millions of dollars each year on safety training. Clear communication and understanding is essential.

8. Summary A well is out of control when reservoir gas or fluids are flowing in a way that cannot be regulated or stopped. The most spectacular and hazardous blowout is a surface blowout when reservoir fluid escapes from a well at the surface. Uncontrolled flows that occur within a well underground can also cause a downhole blowout. When positive fluid pressure is not properly controlled downhole, a kick will likely occur. If the kick is not brought under control quickly, a blowout will occur. A blowout preventer is a series of valves installed on the wellhead to prevent the escape of fluids from the casing and drill pipe.

9. Home Work 1. When does a kick occur? 2. When does a blowout occur? 3. What is a blowout preventer?