proVISION Plus Magnetic Resonance-While-Drilling Service
By providing lithology-independent porosity, pore-size distribution, continuous permeability, and direct hydrocarbon detection, the proVISION Plus service delivers a step change in real-time producibility assessment for complex reservoirs.
Applications
■ Continuous, real-time, lithology-independent porosity without chemical sources
■ Continuous, real-time permeability evaluation
■ Resistivity-independent pay identification
■ Thin-bed characterization
■ Carbonate facies characterization
■ Irreducible water saturation
■ Gas-bearing reservoir evaluation
■ Heavy oil and tar identification
Benefits
■ Optimizes well placement to maximize well productivity
■ Enhances perforation and stimulation design
■ Provides pore size distribution to assess reservoir storage and flow capacity
■ Saves rig time through early formation evaluation
■ Prevents plug-and-abandon and sidetrack decisions by avoiding water-cut situations
Features
■ Real-time, continuous measurement of T2 distribution
■ Calculation from T2 distribution of continuous permeability, lithology-independent porosity, producible and irreducible fluid volumes, and pore size distribution
■ Turbine power to eliminate trips to replace batteries
■ Single-sleeve stabilizer that minimizes motion without affecting tendency
■ Ability to be placed anywhere in BHA
RESERVOIR QUALITY
The proVISION Plus service measures magnetic resonance and complements other LWD data to provide advanced petrophysical evaluation of complex reservoirs in real time. By fully evaluating rock and fluid properties with the proVISION Plus service, you can reveal bypassed pay zones and determine permeability.
Using T2 distribution, the proVISION Plus service calculates continuous permeability, lithology-independent porosity, producible and irreducible fluid volumes, and pore size distribution. These capabilities make it possible to identify pay zones in shaly sands that would otherwise be bypassed and accurately determine permeability in heterogeneous carbonates. This evaluation method provides the final piece for a complete petrophysical answer.
COMPLETION QUALITY
By identifying bypassed pay zones and areas of high permeability, the proVISION Plus service provides information critical to optimizing your completion design. This service provides insight that can improve the effectiveness of your entire completion strategy and creates opportunities to increase production and decrease completion cost.
The service identifies areas of low permeability, helping you make better decisions about where and how to produce. When additional pay zones are discovered, you can use the data to create a targeted completion design.
A two-dimensional measurement of pore and fluid properties
Magnetic resonance (MR) measurements, which reveal pore and fluid properties, consist of a series of manipulations of hydrogen nuclei in fluid molecules. The nuclei have magnetic moments, behaving like small bar magnets, and their orientations can be controlled by magnetic fields. The nuclei also spin, acting like gyroscopes.
T2 distribution
When the proVISION Plus tool approaches the formation, its permanent magnets align the nuclei, starting a measurement sequence. When the tool’s controlled antenna is applied, this alignment is followed by spin tipping, precession, and repeated dephasing and refocusing. Transverse relaxation and longitudinal relaxation limit how long a measurement will last. The relaxation time is a function of pore size and fluid properties.
Completing all these steps only takes a few seconds, and then the measurement is repeated, resulting in a collection of relaxation times. T2 distribution is this collection of all the relaxation times.
Lithology-independent porosity
MR measurements—like neutron porosity logs—are sensitive to hydrogen. The MR signal amplitude is only proportional to the number of hydrogen nuclei present in the fluid. In contrast, the neutron log responds to all hydrogen in the formation, including those that are not part of the pore fluids. Thus, MR provides an accurate porosity measurement, free from chemical sources and independent from lithology effects since the signal includes only producible fluids and capillary-bound water.
Irreducible and producible fluid volumes
T2 distribution mimics pore-size distribution in water-saturated rock. The T2 decay can be further processed to quantify pore volumes associated within different ranges of T2. The volumes of interest typically are the bound fluid in small pores and free fluid that is readily producible from larger pores. An input T2 cutoff is usually selected to define both bound- and free-fluid volume. The same cutoff is used to define the capillary bound water that is used by reservoir engineers to assess the fluid flow in the reservoir.
Facies analysis and pore size distribution
MR signal decay during each measurement cycle—the relaxation time—depends on pore sizes. Small pores shorten relaxation times, and the shortest times correspond to clay-bound and capillary-bound water. The relaxation times for large pores, which contain the most readily producible fluids, are longer. The distribution of relaxation times is a measure of the distribution of pore sizes. The relaxation times and their distributions can be interpreted to give other petrophysical parameters such as permeability, producible porosity, and irreducible water saturation. Other possible applications include capillary pressure curves, hydrocarbon identification, and facies analysis.
Continuous permeability
One of the most important features of MR logging is the ability to provide a real-time permeability log. Log permeability measurements enable prediction of production rates to optimize completion and stimulation programs.
CASE STUDY
Core-Quality LWD Data Identifies Additional Pay Within Carbonate Sequence in Deteriorating Section
First run of proVISION Plus 825 service in Ecuador helps Petroamazonas accurately determine rock properties and enhance production
CHALLENGE
Characterize potential pay zones in well with deteriorating hole conditions along the 12¼-in section.
SOLUTION
Deploy proVISION Plus 825 magnetic resonance-while-drilling service to differentiate between high- and low porosity zones while providing permeability data.
RESULT
■ Achieved core analysis–quality logging results that accurately determined rock properties.
■ Identified an additional sand body with high production potential.
lWd thin-Bed analysis identifies 60% More deepwater Reserves
Magnetic resonance while drilling delivers thin-bed analysis revealing two additional pay zones offshore Africa
Challenge
Evaluate laminated sand–shale sequences in a complex reservoir offshore Africa.
Solution
Use proVISION Plus magnetic resonance while drilling to provide a thin-bed analysis.
RESULT
■Logged high-quality petrophysical data in a single run, characterizing two laminated sand–shale sequences.
■ Achieved 60% increase in calculated reserves by identifying two new pay zones.
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