Closure Pressure Determination via Constant Flow Pumping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional formation testing tools face difficulties in accurately determining closure pressure in tight micro-fractured formations due to the use of reciprocating pumps, which create negative pressure and back pressure, obscuring the deflection point in pressure measurements and leading to errors in flow-back tests.
Innovation Solution
A formation testing system with a downhole tool that includes an isolation device, a power unit with a non-reciprocating pump, and a fluid receiving unit with a constant flow control mechanism, allowing for the creation of micro-fractures and precise measurement of closure pressure through a flow-back test by maintaining a constant or substantially constant flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reciprocating pumps are used in conventional formation testing tools, then fluid can be withdrawn from the formation, but negative pressure and back pressure are created that obscure the deflection point in pressure measurements
Solution Approach 1:
The patent replaces the reciprocating mechanical pump system with a continuous flow pump system. This substitution eliminates the reciprocating strokes that generate harmful back pressure, allowing for clear pressure measurements during flow-back tests while maintaining the ability to withdraw fluid from the formation.
Solution Approach 2:
The patent extracts or removes the reciprocating pump mechanism from the formation testing tool. By eliminating this component, the harmful back pressure and negative pressure effects are removed, enabling accurate closure pressure determination through clear deflection point identification in pressure measurements.
2Productivity
If reciprocating pumps create negative pressure to draw fluid from the formation, then fluid flow is achieved, but the back pressure obscures the deflection point leading to large errors in closure pressure determination
Solution Approach 1:
The patent replaces the reciprocating pump system with a continuous flow pump system that maintains constant flow rate. This substitution preserves the fluid withdrawal capability while eliminating the pressure fluctuations that obscure the deflection point, thereby improving closure pressure measurement accuracy.
Solution Approach 2:
The patent changes the operating parameters of the pump system from reciprocating (variable flow rate with strokes) to continuous operation (constant flow rate). This parameter change eliminates the harmful back pressure effects while maintaining effective fluid withdrawal, enabling accurate closure pressure determination.
3Measurement precision
If constant flow rate is maintained during flow-back test, then deflection point can be clearly identified, but requires non-reciprocating pump system which increases device complexity
Solution Approach 1:
The patent replaces the reciprocating pump system with a continuous flow pump system designed to maintain constant flow rate. While this does increase device complexity compared to simple reciprocating pumps, it enables clear deflection point identification and accurate closure pressure determination, which is the primary measurement objective.
Solution Approach 2:
The patent introduces a constant flow control mechanism as an intermediary component in the pump system. This intermediary device regulates the flow rate to remain constant throughout the flow-back test, enabling accurate deflection point identification while integrating smoothly with the overall pump system.
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 determination of closure pressure by maintaining a consistent flow rate during the flow-back test, reducing errors and clearly identifying the deflection point, thus improving the precision of closure pressure measurement in fractured formations.
Implementation Method 1
Such constant flow rates can be achieved by creating a positive pressure difference between the formation and a chamber in the tool receiving the fluid
Implementation Method 2
maintaining a constant or substantially constant flow rate
Data Source
Figure 1
Figure 2
Figure 3~3A
AI summary
An apparatus for determining a closure pressure of a fractured formation surrounding a wellbore is disclosed. The apparatus, in one embodiment, includes an isolation device for isolating a section of the wellbore, a fluid supply unit for supplying a fluid from the wellbore under pressure into the isolated section of the wellbore to cause a fracture in the formation proximate the isolated section, a receiving unit for receiving fluid from the isolated section at a constant or substantially constant rate due to pressure difference between the formation and the receiving unit, and a sensor for determining pressure of the formation during receiving of the fluid into the receiving unit. The apparatus further includes a controller for determining the closure pressure from the determined pressure.