Category Archives: Well Control

Pore Pressure Evaluation While Drilling Is Important For Well Control

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During a drill well on paper phase, wells might be planned based on available data from offset wells or nearby areas. This information may deviate from the actual drilling phase due to several reasons therefore it is very critical to have good monitoring and evaluating pore pressure while drilling. The actual pore pressure will dictate where to set the casing, how much the actual mud weight should be, what potential problems are, etc.

The actual reservoir pressure obtained while drilling will be used to determine right mud density in order to ensure an adequate primary well control. Besides the well control, the proper mud weight can help us in several aspects such as minimizing lost circulation and pipe sticking and maximizing a rate of penetration. You can achieve the trouble free drilling operation.

pore Pressure evaluation while drilling

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Understand about Formation Pressure in Drilling

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Formation pressure is important information for well planning and operation because it impacts on several things as well control, casing design, drilling fluid program, pore pressure prediction, etc.  We will discuss about formation pressure in a basic term for drilling personnel.

During an era of sedimentation and erosion, little grains of sediment are constantly building above each other, usually in an environment of full irrigation. As the sediment thickness of the base layer increases, the sediment grains are packed strongly near to each other, and some water is excluded from the small pore spaces. Though, if the pore spaces through the deposit sediments are connected to the top pressure surface, the fluid at any depth in the sediment will be same as that which would be found in a simple column of fluid.

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Choke Line Friction Pressure as Kill Weight Mud Approaches the Surface

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Choke Line Friction pressure (CLF) has directly affect on the bottom hole pressure while performing well kill operation in a deepwater operation. You may be able to circulate the kick out of the well without breaking the shoe down with the current mud weight however; the well can be fractured when the kill weight mud reaches the surface due to excessive CLF.

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How Kill Weight Mud and CLF Will Break the Shoe

When the kill mud is circulated from the bit to surface as per the second circulation of driller’s method, drill pipe pressure is held constant and the choke is gradually opened. Once the choke is in the fully open position, the back pressure due to choking back the well is gone but the CLF is still there. With the heavier weight, the CLF with KWM will be more than the CLF with the original mud. If the hydrostatic pressure is more than the fracture pressure, the formation will be broken down.  Let’s take a look at the following calculation to get clearer picture of this topic. Continue reading →

How To Compensate Choke Line Friction For Deep Water Well Control

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Choke line friction pressure will increase bottom hole pressure while circulating to kill the well therefore it must be compensated in order to maintain the bottom hole pressure relatively constant. This section will describe how to compensate the choke line friction while bring pump up to speed.

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