Downhole Fluid Sampling Saturation Pressure Estimation

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Solution Overview

Problem

Traditional methods for estimating saturation pressure in downhole fluid sampling are inefficient due to contamination and pressure changes, leading to inaccurate pumping rates and space constraints in downhole tools.

Innovation Solution

A system and method that uses a downhole tool with a pump, optical spectrometer, and processor to measure fluid properties, estimate future saturation pressure, and adjust flowline pressure to maintain it above the estimated saturation pressure, thereby reducing contamination and optimizing pumping rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional methods are used to estimate saturation pressure, then the process is simpler, but the accuracy is poor due to contamination and pressure changes

Engineering Contradiction:

Improvesaturation pressure estimation accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by continuously monitoring fluid properties and estimating saturation pressure before actual sampling occurs. This allows the system to proactively adjust pumping rates and maintain optimal pressure conditions, preventing contamination before it compromises sample integrity rather than reacting after contamination occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback loops where sensors monitor fluid properties (density, composition, temperature), the processor estimates saturation pressure based on this data, and the system automatically adjusts pumping rates. This closed-loop feedback mechanism maintains pressure above saturation pressure, preventing phase changes and contamination, thereby significantly improving measurement accuracy

Inventive Principle:

Principle #23Feedback

2Productivity

If pumping rate is increased to reduce sampling time, then productivity improves, but contamination increases due to pressure drops

Engineering Contradiction:

Improvesampling speedVSAvoidfluid contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts the pumping rate based on real-time fluid property measurements and saturation pressure estimates. Rather than using a fixed high pumping rate that would cause pressure drops and contamination, the system continuously adapts the pumping speed to maintain pressure above the saturation pressure threshold, enabling fast sampling without compromising sample integrity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the pumping rate parameter dynamically based on measured fluid properties. By monitoring density, composition, and temperature, the system calculates the saturation pressure and adjusts the pumping rate to keep operating pressure above this threshold, thereby eliminating contamination while maintaining high productivity

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If downhole tool volume is reduced to meet space constraints, then device size decreases, but the ability to maintain pressure control is compromised

Engineering Contradiction:

Improvedownhole tool sizeVSAvoidpressure control capability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The system replaces complex mechanical pressure control mechanisms with a computational approach. Instead of using large mechanical components or complex hydraulic systems to maintain pressure, the system uses sensors to measure fluid properties, a processor to estimate saturation pressure, and control algorithms to adjust pumping rates, achieving reliable pressure control in a compact configuration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses parameter changes in fluid density and composition measurements to indirectly control and monitor pressure conditions. By continuously measuring these parameters and calculating saturation pressure, the system maintains pressure control through intelligent pumping rate adjustment rather than relying on large mechanical pressure regulation components

Inventive Principle:

Principle #35Parameter changes

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

This approach allows for efficient sampling by reducing contamination levels faster and maintaining optimal pressure, enhancing the accuracy and efficiency of fluid sampling operations.

Implementation Method 1

an optical spectrometer configured to measure optical densities of the fluid in the flowline using a plurality of wavelengths

Methodology Applied

Scientific EffectOptical density measurement: Absorption Spectroscopy

Data Source

PatentUS10746019B2Method to estimate saturation pressure of flow-line fluid with its associated uncertainty during sampling operations downhole and application thereof

Publication Date: 2020.08.18 SCHLUMBERGER TECH CORP

AI summary

A method includes pumping fluid from outside of a downhole tool through a flowline of the downhole tool with a pump. The method further includes taking a first plurality of measurements over time using at least one sensor and estimating a future saturation pressure of the fluid within the flowline at constant time increments via a processor based at least in part on the first plurality of measurements and a saturation pressure model. The method further includes adjusting the flowline pressure to maintain the pressure of the flowline above the estimated future saturation pressure.