Prediction of Wellbore Position Accuracy When Surveyed With Gyroscopic Tools

Torkildsen, Torgeir; Havardstein, Stein Tjelta; Weston, John; Ekseth, Roger

doi:10.2118/90408-pa

Cited by 45 publications

(8 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Any errors present in the accelerometers will affect the accuracy of the inclination and tool-face estimates (Williamson 2000;Torkildsen et al 2008). Modern surveying tools determine inclination and tool face by measuring orthogonal gravity components using three accelerometers.…”

Section: Georeference Qc Testsmentioning

confidence: 99%

“…Continuous gyro and inertial navigation system (INS) surveys have an accumulative azimutherror behavior, as described by Ekseth (1998) and Torkildsen et al (2008), and it is not practical to QC each individual azimuth output. It is more convenient to examine the propagation of the azimuth error over the entire survey, and the continuous azimuth drift test has been developed for this purpose (Ekseth et al 2007).…”

Section: The Continuous Azimuth Drift Testmentioning

confidence: 99%

“…These oscillations have almost no effect on the position accuracy for the entire survey, and they are therefore not included in the SPE-WPTS gyro-error model (Torkildsen et al 2008). These oscillations have almost no effect on the position accuracy for the entire survey, and they are therefore not included in the SPE-WPTS gyro-error model (Torkildsen et al 2008).…”

Section: The Continuous Azimuth Drift Testmentioning

confidence: 99%

“…Most known wellbore-surveying error models, including the SPE-WPTS MWD error model described by Williamson (2000) and the SPE-WPTS gyro error models described by Torkildsen et al (2008), are based mainly on nondownhole data and on the assumption that a given QC level is met. They are intended to be representative of the average performance of a large number of surveys and for the well-placement accuracy that is expected from a planned survey.…”

Section: Error-model Validationmentioning

confidence: 99%

See 3 more Smart Citations

High-Integrity Wellbore Surveying

Ekseth¹,

Torkildsen

Brööks

et al. 2010

SPE Drilling &Amp; Completion

Self Cite

View full text Add to dashboard Cite

Summary Position-uncertainty estimates are used to determine if there is adequate probability of hitting a geological target, of avoiding collision with offset wells, and of drilling a successful relief well in the event of a blowout. These high-value decisions are based on tool-error-model predictions, the validity of which is highly dependent on the application of rigorous quality-control (QC) procedures to the survey data. Directional surveys that do not conform to their model's error predictions represent a risk in terms of lost production, damage to infrastructure, and loss of life. This paper documents weaknesses in conventional directional-survey QC procedures. Theoretical considerations, statistical analyses of real survey data, and real examples of failed surveys that have made it through conventional QC procedures without detection are presented. The paper defines principles for survey-program design and implementation to eliminate these weaknesses. It proposes a new set of minimum requirements for survey validation. Where the cumulative QC data do not support the model, it is necessary to adjust the model to fit the data. In the longer term, it might be possible to rework the tools and procedures in the hope of meeting the original model's specification, but the uncertainty estimate assigned to a survey must be valid at all times. The methods described in this paper are capable of ensuring valid positional data and should be incorporated into standard practice. However, to implement these techniques correctly and consistently, it is probably necessary to establish a specialized supervisory function, responsible for the integrity of wellbore positioning across a company's entire operation. This paper is the product of a collaborative work within the SPE Wellbore Positioning Technical Section (SPE-WPTS), and combines two previous papers on the subject by Ekseth et al. (2006, 2007).

show abstract

Section: Georeference Qc Testsmentioning

confidence: 99%

Section: The Continuous Azimuth Drift Testmentioning

confidence: 99%

Section: The Continuous Azimuth Drift Testmentioning

confidence: 99%

Section: Error-model Validationmentioning

confidence: 99%

See 2 more Smart Citations

High-Integrity Wellbore Surveying

Ekseth¹,

Torkildsen

Brööks

et al. 2010

SPE Drilling &Amp; Completion

Self Cite

View full text Add to dashboard Cite

show abstract

“…In [ 9 ] an in-drilling alignment (IDA) method was proposed to improve the surveying accuracy. References [ 10 , 11 , 12 ] studied the error models for gyroscope-based MWD. An alternative method is micro-electro-mechanical Systems (MEMS) gyroscope-based INS [ 1 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

A Long-Term Performance Enhancement Method for FOG-Based Measurement While Drilling

Zhang

Tie

2016

Sensors

View full text Add to dashboard Cite

In the oil industry, the measurement-while-drilling (MWD) systems are usually used to provide the real-time position and orientation of the bottom hole assembly (BHA) during drilling. However, the present MWD systems based on magnetic surveying technology can barely ensure good performance because of magnetic interference phenomena. In this paper, a MWD surveying system based on a fiber optic gyroscope (FOG) was developed to replace the magnetic surveying system. To accommodate the size of the downhole drilling conditions, a new design method is adopted. In order to realize long-term and high position precision and orientation surveying, an integrated surveying algorithm is proposed based on inertial navigation system (INS) and drilling features. In addition, the FOG-based MWD error model is built and the drilling features are analyzed. The state-space system model and the observation updates model of the Kalman filter are built. To validate the availability and utility of the algorithm, the semi-physical simulation is conducted under laboratory conditions. The results comparison with the traditional algorithms show that the errors were suppressed and the measurement precision of the proposed algorithm is better than the traditional ones. In addition, the proposed method uses a lot less time than the zero velocity update (ZUPT) method.

show abstract