Multi-packer VIT Tool Buffering Pressure Pulses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Vertical Interference Tests (VITs) face challenges in accurately interpreting pressure transients due to pressure pulses propagating through packer elements, which can lead to interference from hydrostatic columns and borehole noise, limiting the reliability of vertical permeability measurements.
Innovation Solution
A downhole tool with multiple packers is used to create annular intervals within a wellbore, where the middle interval is maintained at hydrostatic pressure or pressurized gas, acting as a buffer to absorb pressure pulses, while the upper and lower intervals are set at formation pressure, allowing for accurate recording of pressure transients without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure monitoring devices are positioned in VIT to measure pressure transients, then vertical connectivity can be tested, but pressure pulses propagate through packer elements causing interference from hydrostatic columns and borehole noise
Solution Approach 1:
A buffer interval filled with compressible fluid (gas or liquid) is introduced between the upper and lower test intervals to absorb pressure pulses and prevent their propagation through the packer elements. This intermediary buffer zone eliminates hydrostatic column interference and borehole noise, allowing accurate pressure transient measurements in both upper and lower intervals simultaneously
Solution Approach 2:
The wellbore is divided into three distinct annular intervals using multiple packers: an upper interval, a lower interval, and a middle buffer interval. This segmentation isolates the pressure testing zones from each other and from the hydrostatic column, enabling independent pressure transient measurements in the upper and lower intervals without mutual interference
2Measurement precision
If packers are used to isolate intervals for pressure testing, then vertical interference can be measured, but pressure pulses propagate through packer elements causing interference
Solution Approach 1:
The compressible buffer fluid in the middle interval, which could potentially cause measurement errors due to its compressibility, is instead utilized as a beneficial pressure-absorbing medium. The compressibility of the buffer fluid allows it to absorb pressure pulses generated during testing, converting what could be a source of measurement error into a useful interference-dampening mechanism that improves overall measurement accuracy
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 method enhances the accuracy of VITs by isolating pressure transients from borehole noise and hydrostatic interference, providing more reliable vertical permeability data and improving reservoir characterization.
Implementation Method 1
the middle interval is maintained at hydrostatic pressure or pressurized gas, acting as a buffer to absorb pressure pulses
Data Source
AI summary
A downhole tool having multiple packers and a controller operable to operate the packers to establish upper, middle, and lower intervals. The controller then establishes the upper and lower intervals at formation pressure, and establishes the middle interval at hydrostatic pressure. The controller then creates a pressure signal in one of the upper and lower intervals and then records a resulting pressure transient in both of the upper and lower intervals. The controller is also operable to establish the middle interval at formation pressure and establish the upper and lower intervals at below hydrostatic pressure but above formation pressure, and then create the pressure signal in the middle interval and subsequently record a resulting pressure transient in the middle interval.