In floating drilling operations, an accidental disconnect or a failure of the marine riser close to the BOP stack will have a considerable effect on primary control. The overbalance in the hole will suddenly be reduced by the difference in hydrostatic pressure between the original mud column in the marine riser above the BOP stack … Loss of primary well control – failure of riser

The following precautions should be observed to ensure that primary control is maintained, whilst tripping, circulating bottoms up after a trip, drilling and circulating on bottom. Records: Accurate records of all operations shall be maintained, particularly of any unusual occurrences. These shall describe all flowline shows. The duration of the occurrence, mud return gradients, chloride … Well Control – Primary Control Techniques

When drilling through depleted and/or fractured reservoirs, total losses are a common occurrence.  In the worst case, if the well penetrates the top of the formation (fracture) above the gas-oil contact there is a high risk of a blowout if insufficient fluid is not pumped down the annulus at all times between encountering total losses … Total Losses and Requirement for Continuous Fill-Up

While monitoring the drilling parameters and maintaining primary control it is also  necessary to prepare in anticipation of an influx and consequent loss of primary control.  This involves the pre-recording of the relevant information. 1. General Pre-planning Pre-planning is important to ensure all personnel involved are aware of the action to be taken during well … Primary Control – Planning Considerations

A kick occurs when the hydrostatic pressure of the mud column in the well is less than the formation pore pressure, providing that the well is capable of producing. The article summarise the effects which may indicate that a kick has taken place: Primary Indicators Increase in mud return flow Note: An increase in mud … Influx Detection

Inflow tests are generally carried out to verify if there is communication with the formation through the casing, a liner lap or past a cement plug (bridge plug). Most of the applications are in connection with testing or squeezed off perforations and casing leaks, testing liner-laps, float shoes and float collars, cement plugs and bridge … Inflow Testing Procedure

This article highlights the guidelines which shall be followed during tripping and drilling in order to avoid taking kicks. During any open hole operation the mud level in the well shall always be full.   Prevention While Drilling The following guidelines shall be observed during drilling: Warning signs that a kick has occurred while drilling … Influx Prevention

How to avoid loss of primary control: mud of adequate density is used; active volumes are sufficient and continuously monitored; any change in density, volume, or return flow from the well to the active mud tanks is detected immediately and prompt corrective action taken; swab and surge pressures are kept to a minimum. Below are … Avoiding loss of primary control

Fluid measuring devices play an important role in the casing design of a well, because the maximum anticipated influx volume is one of the parameters used to calculate maximum safe drilling and casing setting depths. The following measuring devices are available: trip tank, trip tank chart recorder, or trip sheet; pit level indicator/chart recorder with … Fluid measuring devices

Pre-recording of information.Proper secondary well control follows a planned course of action. Pre-recording relevant information avoids unnecessary delay. The following aspects concerning the pre-recording of information are discussed: Kick control worksheet. Checking pump pressure at reduced pump speeds. Establishing the weighting material mixing capacity of the rig. Relationship between bottom hole pressure, formation strength at … Well Control – Preliminary record of information