The reference geomagnetic field is essential and a key parameter to derive precisely the wellbore azimuth from magnetic measurements. The lateral uncertainty of the drilling wellbore is therefore directly linked to the level of accuracy of the reference geomagnetic field.

Our solution enables to reduce well lateral uncertainty by up to 60% by applying dedicated solutions to each well drilled; with a specific focus on short collar correction, In Field Referencing and Multi Station Analysis.

The service involves:

• Bottom hole assembly and magnetic sensor placement analysis and recommendations reduce the risk of unwanted magnetic interference effects on MWD magnetic survey data quality.
• Multi-station analysis and correction with IFR data where available, provide corrected survey azimuths and eliminate the risk of survey data gross errors from the MWD magnetic survey sensor package.
• Advanced processing of legacy offset well data and real time survey batches while drilling is performed asper agreed PathControl survey program.
• Post section survey corrected updates are provided per section and at TD.

Benefits:

• More robust survey program optimization and QAQC
• Achieve tighter azimuth control while drilling
• Improved anti-collision planning with increased safe drillable window below a multi-well or pad
• Reduction of uncertainty for relief well drilling
• Increased target intersection certainty
• Enhanced geomodel data accuracy improving future well placement integrity

The reference geomagnetic properties can be known from various magnetic observatories that measure the earth magnetic field and derive a worldwide magnetic mapping. Earth magnetic models such as IGRF, BGGM and HDGM provide the oil and gas industry such magnetic field mapping. Some models provide fit for purpose results better than others, depending on the survey type, target and engineering application.

To increase the level of accuracy of the reference geomagnetic field model, it is possible to make a direct, spatial and local measurement of the earth magnetic field close or at the location of the drilling operation. This technique is called IFR and stands for In-Field Referencing. It is always also possible to follow the variation of the reference geomagnetic field due to external perturbation during the whole drilling operation to ensure the highest level of accuracy. The best and most efficient way to achieve such high levels of accuracy is by automatically measuring the local magnetic earth field locally by installing a human size automatic magnetic observatory close to the drilling

• Short Collar Correction: Even if MSA should be preferred to correct the azimuth, PathControl can provide Short Collar Correction (SCC) if required. It is a single station correction that is less accurate than the MSA but available to QC old wells’.
• In Field Referencing: The access to local geomagnetic information improves the knowledge of the reference magnetic field that is used to correct the lateral position of the drilled well by using correct magnetic declination and reliable references for the DD to QC the Field Acceptance Criteria. Then, the access to IFR is a true added-value and requirement to apply the MSA.
• Multi Station Analysis: The magnetometers suffer from magnetic disturbances sensor scale, biases and misalignment that distort the survey measurements and lead to lateral uncertainty. The objective of the MSA is to analyze wide number of surveys of the same BHA to characterize its specific magnetic signature, which could be used to qualify the survey quality. Also, it enables to correct for the azimuth error station by station.

With the increased number of wells per platform, the in-fill drilling applications and the production that needs to be optimised using multiple lateral drains, collision avoidance has become even more critical.

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The financial impact of shutting in production wells on platforms or repairing damaged wells for HSE reasons have pushed the industry to develop and implement advanced standards and rules to monitor collision avoidance issues with adjacent producing wells.

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Collision avoidance involves using rules that characterize the proximity between adjacent wells. Collision avoidance determines the allowable well separation, the risk associated to directional planning and the requirement in terms of surveying activities.

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Independent collision scan to cross-check the results of the operator and of the DD contractor is essential in case of collision risk with adjacent wells. With solutions to assess and quantify the drilling risk, our wellbore positioning team can provide operations support and remote services based on probability calculations. This evaluation allows the operator to better appreciate the required prevention and mitigation that need to be put in place.

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Mitigation actions can be put in place, such as drilling while monitoring magnetic interferences with our PCTrack® ranging solution, in order to continue drilling when separation factor defined by the company rule is not above the threshold yet.