Tezislər / Theses

Keywords: 
HPHT wells, mud weight, drilling fluid selection, drilling fluid property, water-
based mud, oil-based mud
 
Oil companies prospect and drill for oil in deeper and more challenging 
frontiers, which are more likely to have high pressures/temperatures was 
allowed by favourable economics than ever before because of the rising 
demand of the world’s energy; however, HPHT prospects might be a difficult 
task. Due to the relatively thin mud weight system, the mud weight which is 
higher for HPHT wells must be precisely managed. Problems of high solid 
loading and barite sag can be occurred due to this high mud weight 
requirement. A high-pressure well as having pressure greater than 15000 psi 
and well that has temperatures above 350 
℉
is considered high temperature 
was defined by the API Technical Report. There are mud types in some 
pressure and temperature intervals: 

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THE 3
rd
 INTERNATIONAL SCIENTIFIC CONFERENCES OF STUDENTS AND YOUNG RESEARCHERS 
dedicated to the 99
th
anniversary of the National Leader of Azerbaijan Heydar Aliyev
76
 Table 1.
Mud types in different pressure and temperature intervals. 
Run 
Sample 
Pressure (psi) 
Temperature Range (
℉
) 
1 
Oil based mud 
5000 
70-550 
2 
- 
10000 
70-550 
3 
- 
15000 
70-550 
4 
- 
20000 
70-550 
5 
- 
25000 
70-550 
6 
- 
30000 
70-550 
7 
- 
35000 
70-550 
8 
Water based mud 
5000 
70-500 
9 
- 
15000 
70-500 
10 
- 
25000 
70-500 
11 
- 
35000 
70-500 
For oil and gas industry, high temperature and high pressure activities 
appear to be a new normal. Drilling into reservoirs with high pressure and 
temperature as well as drilling formations with high bottom hole temperatures 
necessitates a fluid with stable rheological qualities. Loss of viscosity and 
fluid loss control can be occurred by water-based mud, whereas oil-based 
mud can be used so as to withstand high temperatures. Although oil-based 
muds are expensive, there are some advantages of this type of mud, such 
as shale stability, better gauge hole, faster penetration rate, less bit balling 
and reduction in differential sticking, which in turn will result in more proper 
work. Therefore, oil-based mud can withstand higher pressures and 
temperatures than water-based mud. In addition to this, oil-based mud has 
higher failure temperature in comparison with water-based mud. Thus, a 
proper choice for most of the HPHT applications in the event of not violating 
the environmental regulations is oil-based mud. HPHT drilling, on the other 
hand, necessitates the development of an environmentally acceptable water-
based mud. A new water-based mud polymer solution that is ecologically 
friendly has been tested for drilling applications at temperatures up to 232
℃
(450
℉
). Synthetic polymers are newly developed by the system components 
that do not contain chromium or other environmentally harmful materials.