Primary control is the use of drilling fluids of sufficient density to overbalance formation pore pressure. This is particularly important if well control may be complicated by logistical constraints, in hydrogen sulphide environments where materials are more susceptible to failure, or in top hole drilling operations when employing a diverter system.  It is always the aim of a drilling operation to maintain primary control.


Inflow Testing Procedure

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…

Well Control - Loss of Primary Control

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…

Primary Control - Planning Considerations

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…

Loss of primary well control - failure of riser

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…

Avoiding loss of primary control

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…

Influx Detection

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…

Well Control - Primary Control Techniques

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…

Well Control - Flowline Shows

A kick is generally recognised by an instantaneous increase in the rate of mud returns and/or an associated gain in mud volume in the active mud tanks. A flowline show (gas cut or fluid contaminated…

Well Control - Preliminary record of information

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…

Fluid measuring devices

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…

Influx Prevention

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…

Total Losses and Requirement for Continuous Fill-Up

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…

Additional information