Slim Hole Drilling which, for the purpose of well control, means hole sizes of 4 3/4″ and smaller, will impose certain restrictions on well killing techniques and will require well planning to take care of these limitations. 1 General Annular friction losses are an important aspect in Slim Hole Drilling, especially with regards to well … Well Control – Slim Hole Drilling

All hydrostatic pressure-related calculations should be based on true vertical depth values. This means that the standpipe kill graph of a deviated well has a different curve as compared to the graph prepared for a vertical well due to the behaviour of Pdp. It applies only for phase I (balanced method), since the standpipe pressure … Well Control – Deviated and Horizontal wells

When the drillstring is partially or completely out of the hole and a kick is experienced, every effort should be made to safely return the bit to bottom whilst at the same time maintaining well control. The well can be most effectively killed with the bit on bottom. The string needs to be “stripped” into … Well Control – Combined stripping and volumetric method

Well control by the volumetric method is a technique whereby bottom hole pressure is maintained slightly in excess of pore pressure whilst the gas influx is allowed to expand as it migrates to surface. The technique is a temporary well control method to be employed until other/better well control methods can be used to restore … Well Control – Volumetric Method

With this method, the well is killed in two circulations. During the first circulation: the influx is circulated out of the hole using the existing mud. Additional influx is prevented by adjusting the choke to maintain a constant bottom hole pressure slightly in excess of the pore pressure. During the second circulation: the existing mud … Well Control – Driller’s Method

In this method the well is killed in one circulation. The kick is circulated out whilst mud of sufficient density to (over) balance the pore pressure is circulated in. Mud with a density sufficient to balance the pore pressure is circulated at a constant rate. At the same time, to prevent any further influx, the … Well Control – Balanced Mud Method

Recognising a kick and need for immediate action.A kick occurs when the hydrostatic pressure of the mud column in the well is less than the pore pressure of a producing formation.Drilling breaks and gas, salt water, or oil contaminated mud at the flowline are potential signals. A kick however indicate that formation fluid is entering … Well Control – Recognizing a kick and action to be taken