//Drilling Problems

Drilling Problems

Drilling problems can be very costly. The most prevalent drilling problems include pipe sticking, lost circulation, hole deviation, pipe failures, borehole instability, mud contamination, formation damage, hole cleaning, H2S-bearing formation and shallow gas, and equipment and personnel-related problems. There are many problems encountered during drilling process such as :

1. Inadequate Hole Cleaning :
One of the main functions of drilling fluid, such as mud, is to remove cuttings of rock from the bottom of the hole to be transported by circulatory system. Hole cleaning is the ability of a circulating fluid to do so. The major factor to this ability is the velocity of the fluid, along with mud properties and hole inclination. In directional drilling, hole cleaning problem is likely to be met. Insufficient hole cleaning in this angle will lead to build-up of rock cuttings that can cause stuck pipe

Hole Deviation

2. Hole deviation:
Hole deviation is the unintentional deviation of drilling from a preselected path. This problem can result in higher drilling costs and some fatal problems regarding oil production. Operators can recognize this problem through the signals sent by the sensors in the drill string. Some factors that may cause this are drill bit type, stability of drill rig, loose drill strings, and fissile or folded rocks. One means of preventing this is to conduct geotechnical investigations. This test examines the kind of rock and soil the drill bit will encounter

Loss of Circulation

3. Loss of circulation :
Loss of circulation refers to the uncontrolled flow of drilling mud into a formation called a ‘thief zone’. In this problem, loss may refer only to some mud or to all the mud that in the circulation system. A ‘thief zone’ is usually located in formations that are fractured or have high permeability. Monitoring hole cleaning and mud weight maintaining are some actions used to prevent this problem. However if lost circulation has occurred, sealing of the thief zone is done using mixed mud

Picture Source:
https://petrowiki.org/PEH:Drilling_Problems_and_Solutions#Pipe_Sticking

Source:
https://petrowiki.org/PEH:Drilling_Problems_and_Solutions#Pipe_Sticking
http://my-spread.com/files//4131/Hole%20cleaning%20in%20directional%20wells.pdf




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