Learn how to reduce survey errors and enhance well performance with these best practices for directional drilling surveys in the oil and gas industry.

In the last decades there have been terrific improvements for directional and measuring quality and reliability: the error margin has narrowed to a few centimetres by using hi-tech tools. However the request for an high precision tool mainly depends on the type of well: an exploratory well, with a narrow target, may require an high grade of precision, which perhaps is not required for a development well pointing to a huge flat reservoir. Hi-tech tools are expensive, therefore the planning phase must carefully consider requirements Vs available options. My experience with a challenging relief well was amazing: the blowing well was intercepted around 4000m with a 5" flat mill against the 7" prod csg and the well was killed with hi-dens mud.

Last updated on Jul 23, 2024

How can directional drilling surveys be more accurate?

Directional drilling surveys are essential for planning and executing complex well trajectories that target specific reservoir zones, avoid geological hazards, and optimize production. However, survey accuracy can be affected by various sources of error, such as magnetic interference, tool calibration, borehole deviation, and human factors. How can directional drilling surveys be more accurate? Here are some tips and best practices to consider.

1 Use non-magnetic tools

One of the main challenges of directional drilling surveys is to minimize the impact of magnetic interference on the measurement of azimuth and inclination. Magnetic interference can come from the drill string, the casing, nearby wells, or the earth's magnetic field. To reduce this effect, it is advisable to use non-magnetic tools, such as gyroscopes, inertial navigation systems, or acoustic sensors, that do not rely on magnetic measurements. These tools can provide more accurate and reliable survey data, especially in high-angle or horizontal wells, where magnetic interference is more pronounced.

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Kevin Smith

Regional Sales Manager - North America | Clean Energy Specialist | Oil Well Cementing, CCS & HPHT Expert
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Magnetic tools can cause issues in oil and gas drilling because they are susceptible to interference from the earth's magnetic field, nearby wells, and drill string/casing, which can lead to inaccurate measurements of azimuth and inclination, ultimately compromising the overall accuracy of the directional drilling survey.

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2 Calibrate and validate tools regularly

Another factor that can affect survey accuracy is the quality and performance of the survey tools. To ensure that the tools are functioning properly and providing consistent readings, they need to be calibrated and validated regularly. Calibration is the process of adjusting the tool parameters to match a known standard, such as a reference well or a surface benchmark. Validation is the process of verifying that the tool readings are within an acceptable range of error, such as by comparing them with other tools or methods. Calibration and validation should be done before and after each survey run, as well as periodically during the drilling operation.

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Kevin Smith

Regional Sales Manager - North America | Clean Energy Specialist | Oil Well Cementing, CCS & HPHT Expert
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Regular calibration of sensors is a must and the tools should be returned and serviced at shop by the appropriate technicians to ensure the accuracy and dependability of the tool for its next job. In the time I worked in the field as an MWD/LWD Engineer, the slightest suspicion of the accuracy of the tool not being at its optimal performance would lead complications of trust at best but quickly escalated to the Company mans decision of running the service company off site for a replacement. The calibration and validation of tools in the field is crucial.

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3 Correct for borehole deviation

Borehole deviation is the difference between the actual and the planned well path, caused by various factors, such as formation characteristics, drilling parameters, tool wear, or human error. Borehole deviation can affect survey accuracy by introducing errors in the depth, azimuth, and inclination measurements. To correct for borehole deviation, it is necessary to use a mathematical model that accounts for the curvature and tortuosity of the wellbore, such as the minimum curvature method or the radius of curvature method. These methods can calculate the true vertical depth, the true north direction, and the true inclination of the wellbore at any point along the well path.

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4 Apply quality control and assurance

Quality control and assurance are the processes of checking and evaluating the survey data for accuracy, completeness, and consistency. Quality control involves applying various checks and corrections to the raw survey data, such as filtering out noise, removing outliers, smoothing curves, and adjusting for drift. Quality assurance involves comparing and validating the survey data with other sources of information, such as geosteering logs, formation tops, seismic data, or offset wells. Quality control and assurance can help identify and resolve any discrepancies or anomalies in the survey data, as well as improve the confidence and reliability of the survey results.

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5 Train and educate personnel

Human factors are also important for ensuring survey accuracy, as they can influence the selection, operation, and interpretation of the survey tools and data. Therefore, it is essential to train and educate the personnel involved in the survey process, such as drillers, surveyors, engineers, and geologists. Training and education can help them understand the principles and limitations of the survey tools and methods, as well as the sources and effects of survey errors. Training and education can also help them develop the skills and competencies to perform the survey tasks effectively and efficiently, as well as to communicate and collaborate with other team members.

Directional drilling surveys are a vital part of the oil and gas industry, as they can enhance the efficiency and productivity of the drilling operations. By following these tips and best practices, you can improve the accuracy of your directional drilling surveys, and ultimately, achieve your well objectives.

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Maganti Dinesh

Associate Engineer - @ Shell, Wells Reservoir and Facility Management || Project intern at HPCL vizag || Alumni Presidency University Bangalore || Department of petroleum engineering.
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Investing in personnel training is akin to empowering the workforce with the tools and knowledge needed for excellence. By providing ongoing education, businesses cultivate a skilled and adaptable team, fostering innovation, efficiency, and a culture of continuous improvement.

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Hesham Hegab

Drilling Supervisor @ General Petroleum Company | IADC Wellsharp Supervisor | IWCF Supervisor level 4 | TMT Certified
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Very important issue is to train the Engineers and personnel who are involved in the direction survey which short the way to others.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Gianfranco Baccon

Retired from Eni Drlg&Compl
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In the last decades there have been terrific improvements for directional and measuring quality and reliability: the error margin has narrowed to a few centimetres by using hi-tech tools. However the request for an high precision tool mainly depends on the type of well: an exploratory well, with a narrow target, may require an high grade of precision, which perhaps is not required for a development well pointing to a huge flat reservoir. Hi-tech tools are expensive, therefore the planning phase must carefully consider requirements Vs available options. My experience with a challenging relief well was amazing: the blowing well was intercepted around 4000m with a 5" flat mill against the 7" prod csg and the well was killed with hi-dens mud.

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Kevin Smith

Regional Sales Manager - North America | Clean Energy Specialist | Oil Well Cementing, CCS & HPHT Expert
Report contribution
Other considerations to enhance accuracy of drilling surveys include: 1.) Real-time data transmission the ability for the data to be collected and analyzed by Engineers, Geologists, Technicians and Drilling Coordinators will allow for immediate adjustments to drilling directions & instructions. 2.) Multi-sensor tools 3.) High Resolution Surveys 4.) Advanced LWD tools 5.) Integration with 3D seismic data 6.) Increased Frequency of Surveys (This also has negative impact on time) 7.) Using advanced software can enhance calculations for better accuracy of surveys 8) Quality Control Checks: This is another major part of the MWD/LWD Engineers job to look for telltale signs of errors or inconsistencies and to troubleshoot & communicate issues.

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How can directional drilling surveys be more accurate?

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5

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1 Use non-magnetic tools

2 Calibrate and validate tools regularly

3 Correct for borehole deviation

4 Apply quality control and assurance

5 Train and educate personnel

6 Here’s what else to consider

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