Looking Back, Looking Now, Looking Forward – the path of wellbore surveying

Borehole surveying had a dramatic wakeup call in the late 1970’s that led to development of significantly more accurate survey tools. Key industry experts collaborated to create ISCWSA and develop usable models for managing survey uncertainty. There is still some distance to cover to bring all wellbore survey users up to speed and develop new capabilities.

In the 1970’s, the prevailing 1950’s Walstrom random error model was identified as an inaccurate representation of the true wellbore position uncertainty with a huge negative impact on the ability to target a relief well. The Wolff / de Wardt systematic error model replaced Walstrom’s random error model in the early 1980’s leading to the rapid development of higher accuracy survey tools specifically including dynamically tuned (north seeking) gyro instruments.

Industry experts collaborated to form the Industry Steering Committee on Wellbore Survey Accuracy ISCWSA) to dispel the confusion and secrecy commonly associated with wellbore surveying and to enable the industry to produce consistent, reliable estimates of survey-tool performance in today's wells. This industry organization of volunteers has published many papers, e-books, etc. describing error modelling, tool validation, collision avoidance and other critical criteria for calculating and maximizing wellbore accuracy.

In spite of all this publicly available deep knowledge, some operators (typically smaller companies in remoter areas) are far behind best practice when it comes to designing and supervising survey programs to accomplish Blow Out Contingency Plan (BOCP) and subsurface modelling position requirements exposing huge risk and loss of value.

Global survey choices are too often driven by cost considerations despite the negative impact of steering operations (Stockhausen effect) and longer laterals exposing avoidable wellbore position uncertainty. Development of tortuosity measurement and description has lagged the needs of completion and production especially in long laterals. Digitalization and automation of drilling planning / operations is advancing rapidly generating new demands on data gathering, transmission and usage.

This presentation will describe industry shortfalls in wellbore survey knowledge application along with their consequences. A view to the future of wellbore surveying to meet customer (completion / production / subsurface) needs to deliver greater value as wells become more challenging will be presented.