Torus Wedge Flowmeter for Unscreened Mud Kick Detection
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Solution Overview
Problem
Conventional methods for measuring the flow rate and density of drilling mud exiting a wellbore are ineffective in detecting early kicks due to limitations in measuring unscreened mud containing cuttings and solids, leading to potential loss of well control.
Innovation Solution
A system that measures flow rate and density directly at the wellhead using a torus wedge flowmeter and high and low pressure diaphragm seals, integrated with a programmable logic controller to calculate flow rates and densities before the mud is screened, enabling detection of sharp fluctuations and low flow rates indicative of pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flow meters and density meters are used to measure screened mud after shakers and screens, then measurement reliability is improved, but early kick detection capability deteriorates
Solution Approach 1:
The patent applies preliminary action by measuring mud flow rate and density at the wellhead before the mud passes through shakers and screens. This positioning allows the system to detect kicks in real-time as they occur at the source, rather than after the mud has been processed. The measurement system is installed on the wellhead itself, enabling early detection of pressure differentials and flow rate changes that indicate a kick, thus preserving critical information that would be lost if measurements were taken downstream after screening.
2Device complexity
If pressure transducers are used to infer flow rate from pressure in the annulus, then measurement system complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces indirect pressure-based inference with direct flow rate measurement using a flow meter installed at the wellhead. Instead of using pressure transducers to infer flow rate from annulus pressure (which provides only indirect and imprecise data), the system directly measures the actual flow rate of mud exiting the wellbore. This substitution of measurement methodology dramatically improves precision while the overall system remains relatively simple in design.
Solution Approach 2:
The patent introduces a diaphragm seal as an intermediary between the harsh mud environment and the pressure sensing elements. The diaphragm seal allows pressure measurements to be taken without direct exposure of sensitive transducers to the mud, cuttings, and debris. This intermediary protects the measurement system while enabling accurate pressure-based flow rate calculations, thus improving measurement precision without significantly increasing system complexity.
3Measurement precision
If density is measured using siphoned fraction with Coriolis meter, then density measurement accuracy is improved, but adaptability to unscreened mud deteriorates
Solution Approach 1:
The patent uses a diaphragm seal as an intermediary that allows the density measurement system to directly contact and measure unscreened mud containing cuttings and solids. The diaphragm seal transmits pressure information from the harsh mud environment to the density meter without requiring the mud to be siphoned or filtered. This enables the system to measure the density of the actual returning mud as it exits the wellbore, improving adaptability to unscreened mud while maintaining measurement accuracy.
Solution Approach 2:
The patent extracts the density measurement capability from the downstream screened mud environment and relocates it to the wellhead where unscreened mud is present. By installing the density meter with diaphragm seal protection at the wellhead, the system directly measures the density of mud as it returns from the formation, capturing the true density including the effects of kick-informed fluids. This extraction of the measurement function to the source location improves adaptability to unscreened mud conditions.
4Device complexity
If flow meters are installed after shakers and screens, then device complexity is reduced, but measurement precision for low flow rates deteriorates
Solution Approach 1:
The patent applies preliminary action by installing the flow meter at the wellhead to measure mud flow rate before the mud passes through shakers and screens. This positioning allows the system to capture and measure even very low flow rates as they first occur at the wellhead. The flow meter is strategically placed to detect the initial flow changes that indicate a kick, providing precise measurements of low flow rates that would be difficult to detect downstream after the mud has been processed and mixed in the mud pit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and timely detection of potentially dangerous kicks by measuring unscreened drilling mud parameters, preventing uncontrolled flow of formation fluids and improving well control management.
Implementation Method 1
The torus wedge flowmeter is used to detect flow rate for mud leaving the wellbore
Implementation Method 2
Density of drilling mud exiting the wellbore is detected using high and low pressure diaphragm seals on the riser with associated high range and low range differential pressure transmitters
Implementation Method 3
high and low pressure diaphragm seals on the riser with associated high range and low range differential pressure transmitters
Data Source
AI summary
A mud flow measurement apparatus is described which is capable of measuring mud flow rate and density at or near the wellhead during a drilling operation. A riser assembly includes a torus wedge meter and density detection elements which are interconnected with a flow computer. Flow parameters are measured for unscreened drilling mud exiting a wellbore.