Comparison

Advantages of high precision Atlas gyro

High-precision gyro survey instruments are one of the promising and rapidly developing areas of specialized equipment for the oil and gas and mining industries. Atlas Drilling north-seeking gyro is superior in accuracy to MWD and EMS tools. At the same time, a memory drop gyro is capable of operating in cased wells and is not subject to magnetic interference errors. Below, we suggest that you familiarize yourself with the results of the analysis of the accuracy of the Atlas Drilling drop gyro with other survey instruments.

The relevance of the use of high-precision gyroscopes

автономный сбрасываемый гироскоп Атлас
Atlas Drilling Memory Drop Gyro

The depletion of hydrocarbon reserves and the complexity of development lead to the use of advanced and highly efficient technologies. In the field of geosteering, high-precision gyroscopy technology plays a significant role for safe and efficient wellbore positioning. In recent years, leading oil and gas companies have tightened control over compliance with the following criteria when drilling:

  • high-precision determination of the wellbore position in order to correct the trajectory during drilling and optimize its trajectory; 
  • prevention of wellbore intersections; 
  • detailed verification of compliance of the actual wellbore trajectory with the project one

Atlas Drilling North-seeking drop gyro is excellent at solving these and other challenges in well navigation and positioning.

Tools for comparison

For comparison, four survey tools were taken: 

  • ATLAS GYRO – memory drop north-seeking gyro by Atlas Drilling (ISCWSA uncertainty model Atlas Drilling gyro);
  • MWD – standard directional drilling system (ISCWSA uncertainty model MWD standard);
  • MWD+HDGM+SAG+MS – MWD system that uses corrections to increase accuracy (ISCWSA uncertainty model MWD+HDGM+SAG+MS);
  • EMS -magnetic survey tool (ISCWSA uncertainty model EMS standard).

Comparison is made by calculating the error ellipse (3 sigma) for individual well trajectories. Next, graphs of the increase in Lateral (horizontal) and vertical errors with depth were plotted. All depth in meters.

Example 1 - Comparison of Atlas Drilling gyro with other survey tools

As a first example, a horizontal well with a total depth (TD) of 4000 meters was taken. The length of its horizontal section is 2300 meters, and the vertical depth (TVD) is 1200 meters.

Well 1 -3D trajectory

Calculations of Lateral (horizontal) (+/-) and Vertical (+/-) tool errors:

compare atlas drop gyro

Ellipses of uncertainty and their area:

compare Atlas drop gyro
atlas drop gyro compare
Well 1 - Ellipses of uncertainty

So, the lower the survey uncertainty, the more accurate the tool is considered. At the bottom of the well (4000 m) we have the following values for the measurement uncertainty of the compared instruments:

EMS tool                              –  Lateral error +/- 311 m,       Vertical error +/- 38 m,      error ellipse area 11,525 sq.m.      

MWD                                    –  Lateral error +/- 307 m,      Vertical error +/- 38 m,     error ellipse area 10,368 sq.m.

MWD+HDGM+SAG+MS  –  Lateral error +/- 169 m,      Vertical error +/- 22 m,      error ellipse area  4,156 sq.m. 

Atlas Drilling Gyro            –  Lateral error +/-  66 m,      Vertical error +/- 12 m,       error ellipse area  1,479 sq.m. 

results of example No. 1

Thus, we see that the Atlas Drilling memory drop gyro is 2.6 – 4.7 times more accurate in the horizontal plane, and 1.8–3.2 times more accurate in the vertical plane. At the same time, the total measurement uncertainty area is 2.8–7.8 times lower

In other words, the use of an Atlas Drilling drop gyro increases drilling accuracy and reduces financial risks:

                    – by 64% compared to MWD with corrections;

                    – by 86%  compared to standard MWD.

The EMS survey tool mainly used by wireline service companies is significantly lower in accuracy comparing to MWD and cannot be a reliable tool for control the wellbore trajectory.

Example 2 - Comparison of Atlas Drilling gyro with other survey tools

As a first example, a horizontal well with a total depth (TD) of 4900 meters was taken. The length of its horizontal section is 2300 meters, and the vertical depth (TVD) is 1200 meters.

Well 2 -3D trajectory

Calculations of Lateral (horizontal) (+/-) and Vertical (+/-) tool errors:

Ellipses of uncertainty and their area:

atlas drop gyro compare
Well 2 - Ellipses of uncertainty

So, the lower the survey uncertainty, the more accurate the tool is considered. At the bottom of the well (4900 m) we have the following values for the measurement uncertainty of the compared instruments:

EMS tool                              –  Lateral error +/- 124 m,       Vertical error +/- 32 m,      error ellipse area 11,047 sq.m.      

MWD                                    –  Lateral error +/- 121 m,      Vertical error +/- 31 m,     error ellipse area  8,802 sq.m.

MWD+HDGM+SAG+MS  –  Lateral error +/-  65 m,      Vertical error +/- 18 m,      error ellipse area  3,387 sq.m. 

Atlas Drilling Gyro           –  Lateral error +/-  46 m,      Vertical error +/- 11 m,       error ellipse area  1,465 sq.m. 

results of example No. 2

Thus, we see that the Atlas Drilling memory drop gyro is 1.4 – 2.7 times more accurate in the horizontal plane, and 1.6–2.9 times more accurate in the vertical plane. At the same time, the total measurement uncertainty area is 2.3–7.5 times lower

In other words, the use of an Atlas Drilling drop gyro increases drilling accuracy and reduces financial risks:

                    – by 57% compared to MWD with corrections;57

                    – by 83%  compared to standard MWD.

The EMS survey tool mainly used by wireline service companies is significantly lower in accuracy comparing to MWD and cannot be a reliable tool for control the wellbore trajectory.

Conclusion

The memory drop gyro is superior in accuracy to MWD and wireline EMS tools. Therefore, the Atlas Drilling high-precision gyro is a reliable tool for control of the well trajectory. Atlas Drilling offers the highest quality solutions in the field of wellbore positioning and geosteering in compliance with the best QA/QC standards.