Abstract
The objective of this paper is to evaluate the effectiveness of a distributed pressure sensor array along the drillstring in identifying and quantifying fluid influx into the wellbore.
As part of a real-time wired drillpipe (WDP) network, distributed sensors can be spaced along the network at varying intervals. In the fall of 2020, a test well was drilled where such a WDP network was utilized, involving 11 discrete sensor packages. These distributed sensors consisted of absolute annular and internal pressure transducers. From these distributed sensors, analysis of various intervals was examined for fluid effects including density analysis. This paper summarizes the findings of the tests and analyses.
The WDP network (Craig, et al. 2013) is the underlying technology that allows for the distributed sensor array and the real-time processing of measured data. Each discrete sensor package is a node on the network. The industry-leading telemetry bandwidth of the WDP network allows for many sensor nodes. The test well drilled in the fall of 2020 gave an opportunity to place 11 sensor nodes along the drillstring. The real-time absolute pressure data collected from these nodes was analyzed for various intervals, calculating differential pressure between pressure sensor nodes and further calculating interval fluid density.
The results of the distributed absolute pressure data provided many interesting observations. The effectiveness of the interval density for quick-look monitoring was greatly enhanced from the more traditional view of the raw pressure data alone. The effects of sensor spacing and sensitivity were easily observed. Tracking variations in fluid density as it transitions through the wellbore can provide insight into fluid mixing, fluid velocity, and transmission time. Transmission time through the various intervals can further provide insight into wellbore conditions. The slope and peak of interval fluid transitions help understand volumetric and specific density details of fluid transitions from events such as drilling mud pills and influx materials.
This novel dataset showcases the power of a real-time distributed sensor array. Multiple intervals of interest can be examined, leading to a new level of wellbore understanding. Information concerning the wellbore fluid can aid in real-time decision making to optimize the wellbore and associated operations, while providing a new level of risk avoidance and safety factor.
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