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
There are four principal causes of loss of primary control: swabbing, insuficient fluid density, losses, failure to fill the hole correctly. 1 Swabbing Swabbing can also be caused by pulling full gauge tools which restrict the passage of fluid in the annulus. This creates a piston effect and the volume below the tool would be … Well Control – Loss of Primary Control
For exploratory well, the prediction of abnormally pressured formations can be difficult. Correlation with nearby wells will provide the most reliable information. Before drilling a wildcat, seismic data will generally be the only source of information regarding abnormal pore pressures. Different indications of abnormal pore pressures will be observed in clastic and impermeable formations: Indications … Well Control – Abnormal pore pressures
This article descrobes the drilling program and other Well Design considerations for Well Control 1 Drilling programme The drilling programme is based on the information provided by the subsurface department and in summarized in the Well Planning Datasheet. It should include in particular: A statement on shallow gas. Formation characteristics: permeability, fluid type, hydrocarbon depths, … Well Control – Well Design
Some areas are notorious for the presence of hydrostatically pressured gas pockets at relatively shallow depths. 1 Prediction of shallow gas Although the location of gas pockets is difficult to predict, high resolution seismic data acquisition, processing and interpretation techniques increase the reliability of the shallow gas prognosis and therefore, surveys are to be recommended. … Well Control – Shallow Gas
this article discuss the suitability of barrier for the following: Fluids Mechanical Barriers in completed Wells Sub-surface Safety Valve Sustension of a perforated well (with xmas tree) Sub Sea Well Suspensions Two Way Check Valve (TWCV) 1. Fluids as a Barrier Only drilling mud can be defined as a truly independent fluid well barrier. It … Discussion on Suitability of Barriers (well control)