The Modular Formation Dynamics Tester (MDT) tool consists of individual modules that can be configured to meet almost any testing and sampling need. A new high-accuracy, high-resolution quartz gauge with a fast dynamic response provides formation and hydrostatic pressure measurements. Sensors mounted in the flowline provide measurements of formation fluid resistivity and temperature while fluid flow is controlled from the surface.
The tool configuration, including a single-probe module and 1-, 23/4, and 6 gallon sample chambers, allows multiple pressure measurements and the recovery of multiple fluid samples during the same trip in the well. Adding a pumpout module to the tool string greatly enhances the fluid sampling operation. A multisample module allows the retrieval of six 450 cc pressure-volume-temperature (PVT) -quality samples.
Quick, accurate pressure measurements provide dynamic profiling.
MDT pressure gauges exhibit improved dynamic response with no compromise in accuracy--and precise flowline control during testing ensures monophasic flow. Together, these unique features contribute to efficient, accurate determination of permeability.
By running two probe modules, contiguous sands can be monitored during an interference test. The MDT two-probe configuration also enhances pressure gradient measurements, since the distance between the two measuring points is precisely known.
Interpretation of data from the MDT three-probe configuration provides an evaluation of horizontal and vertical permeabilities and formation heterogeneity. A spatial distribution of permeability can then be computed from a profile of the tests.
The larger borehole wall area tested with the MDT packer tool provides a pressure buildup with a much deeper radius of investigation. Where there are safety, environmental, and economic considerations, this small-scale DST-type test offers several advantages over conventional DST tests.
Real-time tool control facilitates
interpretation.
The MAXIS-500 service unit controls the sampling pressure and pretest flow rate and volume from the surface. This control reduces the hydraulic shock to the formation that can contribute to flowline plugging or loss of seal. In addition, full surface control of the downhole tool allows selection of optimum sequences of flow periods during a test.
With the MDT flow control module, flow rate and draw-down pressure are precisely regulated--even during a one-liter test. Sampling pressure can be kept above the bubblepoint pressure of the fluid, which eliminates the need for multiphase interpretation, preserves the sample integrity and allows good permeability measurements.
Many fluid samples can be taken in just one trip downhole.
The MDT tool collects formation fluid through a probe that is placed hydraulically against the borehole wall. Controls from the MAXIS 500 service unit direct this fluid into any selected sample chamber.
The tool is equipped with additional sample chamber modules to collect several PVT-quality samples during a single trip into the hole. A number of different zones can be tested on the same trip, and multiple samples can be collected from a single zone.
Resistivity measurement aids fluid identification.
Flowline resistivity mesurements taken by the probe module help discriminate between formation fluids and filtrate from water-base muds. Real-time resistivity measurements, performed during sampling, allow the dumping of formation fluid until an uncontaminated sample can be obtained.
POTENTIAL FUTURE APPLICATIONS:
Paleo/Sediment Legs: The recovery of in situ pore fluid would provide samples for analysis of noble gas concentrations (e.g. Xe, Kr, Ar) whose ratios allow a measure of past temperature change in deep water. In situ sampling into pressurized chambers avoids problems of bubble contamination and exchange with atmospheric gasses associated with other methods.
Hydrothermal Fluids: Analysis of low temperature hydrothermal processes have been based on the interpretation of samples venting at the seafloor and from pore fluids extracted from recovered core. Results are diminished by poor core recovery (e.g. Leg 158). The MDT samples provide continuous profiling to assess hydrothermal alteration, water/rock interactions and fluid chemistry.
Nankai: MDT testing in isolated intervals would allow for analysis of permeability and fluid flow while the JR is on site. Deployment of a multi-level CORK provides similar information although it is acquired over an extended period of time.
OPERATIONS:
The deployment of MDT will constitute the first step toward deployment
of a variety of large diameter tools. The Diameter for MDT is large (approx.
6-in.) and will require a drillpipe-conveyed deployment for ODP use. A
special BHA sub and tool connections can be assembled with standard ODP
packers for this purpose.
Each sample requires a packer set and pumping time to evacuate the interval. A specialized MDT engineer is also needed.
POSSIBLE
CONFIGURATIONS
Schematic of the MDT tool. Advantages of this tool include:
1. Accurate pressure measurements
- sampling pressure dynamically
controlled
2. Fluid sampling capabilities
- fluid resistivity and optical
properties analyzed
- multiple PFT-grade samples
can be obtained in one pass
3. Estimation of horizontal and vertical
permeability components
- multiple probes produce
direct anisotropy measurements
4. Packers allow sampling under difficult conditions
MDT Tool Specifications
|
|
|
|
|
|||
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* 350°F (175°C) and 15 kpsi with the CQG quartz gauge and/or the optical fluid analysis module ** 250° F (120° C) in oil-base mud # Maximum hole size depends on the packer installed. Larger packers are available for larger hole sizes.
|
||||||
|
|
|
|
|
|
|
|
||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* H2S and mercury compatible
|
|||
Pressure Gauge Specifications
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| * 90% confidence limit | ||
The innovative, high-resolution, CMR Combinable Magnetic Resonance tool provides a free-fluid-index measurement, a permeability estimate, and lithology independent porosity not available with any other tool. It is a pad-type tool that can be used to log holes 6.5 in. and larger in diameter. The CMR tool provides continuous, reproducible measurements with excellent vertical resolution (6-in.) to identify very thin permeable zones. Measurement accuracy is improved because the compact magnet and antenna sensor package is mounted in a pad-like skid that is pressed against the borehole wall.
The CMR signal is processed to estimate the distribution of pore sizes. This is a fundamentally new wireline formation measurement you get only with the CMR tool.
- Gas Hydrate legs (determination of in situ non-frozen gas volume)
- Determination of Permeability in accretionary prism environments
Length 14 ft [4.3 m]
Minimum hole size 6.5 in. [7.8 in. with bowspring]
Maximum temperature 350°F [175°C]
Maximum pressure 20,000 psi
Weight 300 lbm [136.3 kg]
Measurement aperture 6 in.
Depth of investigation 1 in.