Abstract
Pressure testing in the oil and gas industry is used to validate the safety and integrity of equipment across a well barrier. Negative testing, also known as inflow testing, requires a negative pressure differential between the well and the formation. This type of pressure testing is used in well systems to test the integrity of a well barrier envelop. The most infamous negative test in oil and gas history was the test on the Macondo well, shortly before the tragic incident unfolded.
Current practices vary across the globe, they depend on regional regulations, industry standards, location, and company procedures. The two basic types of approaches are based on analysing volume or pressure data. The most common methods are no-flow, pressure monitoring, and Horner. Volume typically is measured using tanks, buckets, and beakers. Pressure traditionally was measured using an analogue pressure chart recorder, which now is increasingly being replaced by real-time data systems. As the oil and gas industry moves towards digital systems for pressure testing, the need for a systematic methodology with clearly defined criteria for negative pressure testing becomes ever more important. Computers cannot interpret ambiguity, so it is essential that a systematic methodology for negative pressure test acceptance is clearly defined, and criteria are developed.
This paper proposes a systematic approach aimed at enhancing the interpretation and standardisation of negative pressure testing results with human factors at its core. Drawing from existing literature and an analysis of over 100 negative tests conducted by the operator, seven key principles are established. These principles serve as a unified framework for interpreting negative test results and provide the much-needed detail for automating the acceptance process. Through their application in diverse testing scenarios in deepwater environments, this work identifies potential inconsistencies in the current methodologies and proposes strategic adjustments. The aim is to foster a more robust and standardised approach to negative pressure test interpretation, enhancing safety, compliance, and operational efficiency in the oil and gas industry.
