Private Forums
position uncertainty
20 June 2018

Hello,

There are a lot of number coefficients in ipm files for error models.

I would like to know about formulas for calculations ellipse of uncertainties.

Do you have any information about cni , cna coefficient's for blind, blind_trend model? 

 



3 answer(s)
mhayes
Director
Stanfield-Hayes Consulting
Total Posts: 33
Join Date: 25/03/11
To add to Nick’s papers can I suggest the original paper for MWD survey accuracy. Though this has been surpassed it is the basis for the ISCWSA models, and thus worth a look:

Williamson, H. S. (1999, January 1). Accuracy Prediction for Directional MWD. Society of Petroleum Engineers. doi:10.2118/56702-MS

regards

Martin

NickG
Consultant
GeoPetra Ltd
Total Posts: 9
Join Date: 16/11/15
Also, you could take a look at the Industry Steering Committee on Wellbore Survey Accuracy (ISCWSA) website, whch is found at http://www.iscwsa.net/
NickG
Consultant
GeoPetra Ltd
Total Posts: 9
Join Date: 16/11/15
Hello Zarif,

I recall that there was a similar my-spread technical discussion entitled "Confidence in surveys" recently (i.e. March 2018), which is linked below.

http://my-spread.com/discussions/5949

My reply to that original discussion is copied below. Hope it helps with your research studies.

Regards, Nick Gibson, GeoPetra Ltd

================================================

Hello, 

I am not sure that my reply specifically answers your  question, however ... Steve Sawaryn has written several SPE technical papers on directional survey calculations and also EOU, the details of which are as listed below.

Regards, Nick Gibson, GeoPetra Ltd

(1) A Compendium of Directional Calculations Based on the Minimum Curvature Method in www.onepetro.org/journal-paper/SPE-84246-PA

(2) A Compendium of Directional Calculations Based on the Minimum Curvature Method--Part 2: Extension to Steering and Landing Applications in www.onepetro.org/journal-paper/SPE-159840-PA

(3) Explicit Calculation of Expansion Factors for Collision Avoidance Between Two Coplanar Survey-Error Ellipses in www.onepetro.org/journal-paper/SPE-159840-PA

(4) Well Collision Avoidance Management and Principles in www.onepetro.org/conference-paper/SPE-184730-MS

(5) Well Collision Avoidance - Separation Rule in www.onepetro.org/conference-paper/SPE-187073-MS
Jump to top of the page