What Can Go Wrong And How To Deal With It: One Company's Experiences
Authors: Adams N.J. , Kuhlman L.G. 
Published: October 2008

Oil well firefighters and blowout specialists see well control problems from a slightly different view than most industry personnel. Often, the well control event "has gone wrong"and developed into a bad problem usually resulting in a blowout. Several situations occur with some frequency and, with proper actions, can be avoided or the damage can be mitigated

This paper describes some of the situations and possible solutions, or "what can go wrong and how to deal with it."Topics to be addressed are as follows:Shallow gas handlingDeep kicksWorkoversEvacuationProcedure compliance

Some solutions are simple and straight forward Others are more difficult to implement

Recommendations are given relative to using blowout computer databases and blowout specialists in contingency planning. Other topics to be addressed are pollution and terrorist - related safety.

INTRODUCTION

Blowout specialists see well control problems differently than typical well control specialists interested in kick killing. The kick situation has become uncontrolled and is a blowout

Events leading to some blowout types will be discussed in this paper as an aid in focusing on ways to prevent the situation. The discussions are based on the experiences of one company specializing in blowout control where its team members have a combined 100 years of well control and drilling experience.

Selected experiences are discussed. Selection criteria for the topics include occurrence frequency and problem severity. Omission of other topics in the paper does not suggest lack of importance in some situations.

Topics for discussion are as follows:Shallow gas handlingSelected deep kick situationsWorkoversEvacuationProcedure compliance

Each is considered in following sections

SHALLOW GAS HANDLING

Shallow gas can be defined several ways. The first is gas encountered at shallow depths for which the fracture gradients are low and do not allow kicks to be controlled with conventional techniques. These depths range from initial soil penetration down to the casing setting point for either conductor or surface casing,

Another common type of shallow gas blowout includes those blowouts occurring in open hole below conductor or surface casing, or behind surface casing caused by phenomena such as gas migration through cement, The flow cannot be closed in and killed with conventional techniques.

Shallow gas blowouts have caused more offshore drilling rigs to be lost than any other type of well control problem. There have been many other cases where shallow blowouts resulted in severe rig damage although the rig was not totally lost. (See Adams and Kuhlman, SPE 19917, for tabular listings of rig damage caused by shallow gas,)

Kick Prevention, A shallow gas flow is a critical issue. Field experience and mathematical modeling have shown it is difficult, and almost impossible, to control or stop a flow with existing rig equipment once it begins. Formation bridging is responsible for stopping many shallow blowouts. Often shallow gas blowouts that do not bridge have to be controlled by some remedial technique or a relief well,