1 Management summary This document provides background information on the subjects of relief well planning, homing-in logging method selection, logging optimization and analysis of the obtained information. Knowledge of the capabilities and limitations of homing-in logging should allow to develop a blowout contingency/abandonment plan at an early stage of well planning. In particular for slimhole … Relief Well – Homing-In
This article describes the keys elements for the stripping method for well control This procedure is recommended when the drill string is partially or completely out of the hole. The basic principle of this technique is to maintain the BHP constant with the well closed and while running drill pipe. This will be achieved by … Well Control – Stripping Method
this article describes the contingency Stock Levels for Well Control. Contingency Fluid Requirement for contingency fluid for onshore operations depends on proximity of supply base. For offshore operations, in order to sustain control in case of severe losses, sufficient contingency fluid stock has to be kept on site. A minimum stock of contingency fluids (excluding … Contingency Stock Levels – Well Control
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
Hydrogen sulphide (H2S) is one of the most toxic of all naturally occurring gases. It occurs world-wide in various concentrations in the scope of the drilling industry. It is explosive and heavier than air. In small concentrations it has an offensive rotten egg odourwhile greater concentrations can paralyse the olfactory nerves so no odour is … Hydrogen Sulphide (H2S)
The gas readings are obtained by the mud loggers from gas analysis equipment and are classified according to the operation that releases the gas into the borehole (background, drilled, connection, trip, etc.) 1. Definitions Drilled gas: Gas that is produced from the volume of cutting drilled. It is usual to record peak drilled gas level … Mud Log Gas (background, drilled, swab, connection, trip)
During drilling and workover operations the consequences of leaks or kicks with sour gas or crude may be very serious. Personnel can be incapacitated by relatively low concentrations of H2S in a very short time and equipment can suffer catastrophic failure due to H2S embrittlement. The H2S risk depends primarily on the H2S content of … Well Control – H2S
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
If normal well killing techniques with conventional circulation are not possible or will result in critical well control conditions, bullheading may be considered. Mud/influx are displaced/squeezed back downhole into the weakest exposed open hole formation. Bullheading may be considered when the following well control situations occur: H2S influx cannot be handled safely by rig personnel … Well Control – Bullheading
When the standard well control method (drillers’ or weight and wait) are not suitable, alternative methods can be considered: Stripping, bullheading, volumetric, off-botton, no circulation, etc 1. Stripping This procedure is recommended when the drill string is partially or completely out of the hole. The principle of this technique is to maintain the BHP constant … Non-conventional well control methods