Page 312 - Drilling Technology in Nontechnical Language

13

DRILLING PROBLEMS AND

SOLUTIONS

Overview

There are various common problems that might occur during drilling,
and there are some uncommon ones, too. This chapter will describe the
most commonly encountered drilling problems caused by downhole
conditions (as opposed to events such as surface equipment failure).
When any problem is encountered, the drilling staff must identify the
root causes of the problem before a proper response to solve the problem

can be formulated. If the root causes are incorrectly identified, it is
unlikely that the correct response will be made, and the problem might
remain unsolved. It can even make the situation worse. Identifying the root
causes of problems covered in this chapter will be described, along with
possible responses.

Lost Circulation

As mentioned in chapter 3, lost circulation occurs in varying degrees.
Losses up to 30 barrels an hour (bbl/hr) would be called seepage losses.
This condition is usually caused by drilling through very permeable
formations where the mud cannot form an effective filter cake.

Between 30 and 60 bbl/hr of mud lost per hour would be called
moderate losses. Again, this is likely to be caused by high-permeability

formations and an ineffective filter cake. It could also be caused by faults
that do not seal but allow mud to enter into the fault system.

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