Advanced Analysis of Magnetic Resonance Finds Laminated ...
Transcript of Advanced Analysis of Magnetic Resonance Finds Laminated ...
CHALLENGEDiscriminate intervals with the best produc-tion potential in what appears to be uniform matrix on standard log suites.
SOLUTIONRun the newly developed 50-burst mag-netic resonance acquisition application in combination with the Three-Detector Lithology Density (TLD) tool to discern both extremely low-porosity and medium-porosity laminations though statistical analysis.
RESULTSUsed the improved ability to locate oil-bearing laminated intervals to optimize placement of four additional laterals.
Conventionally undifferentiated shales Standard log suites, which were developed for conventional reservoirs, characterize the Eagle Ford shale play as a uniform matrix. Analysis of logs with this conventional resolution cannot easily find where the best potential for oil production may occur.
Fifty-burst magnetic resonance application and high-resolution density Magnetic resonance logging has long been applied to discern moveable from nonmoveable fluids regardless of the matrix, which is of great utility in clay-bearing formations. The new 50-burst application improves the statistics for the smallest pores by enabling the collection of more data by an advanced prepolarizing magnetic resonance tool. The result is a 6-in or greater resolution of the clay-bound micropore region of the rock.
The TLD tool uses three detectors to obtain a high-resolution 8-in density output. The TLD detector with 2-in resolution is normally applied to correct for minor wellbore changes resulting from the hole condition and mudcake. In the Eagle Ford the matrix is primarily carbonate and the well-bores are typically smooth. This logging environment allows use of the 2-in detector as a stand-alone porosity device to improve the visibility and reliability of the TLD curves.
Visible laminated payThe Eagle Ford is highly laminated with thin laminations. Run with a conventional logging suite, the 8-in-resolution density cannot differentiate laminations with substantial porosity. However, logging analysis combining the 50-burst magnetic resonance application and high-resolution TLD readily identifies laminated pay by differentiating very small pores, micropores, and poten-tially oil-bearing matrix. Standard-resolution analysis presents only an average of the matrix, which cannot discriminate laminations.
CASE STUDY
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Advanced Analysis of Magnetic Resonance Finds Laminated Pay, Eagle Ford ShaleMatrix nonuniformity detailed by combining 50-burst magnetic resonance application and high-resolution density logging
CASE STUDY: Laminated pay identified by advanced magnetic resonance analysis, Eagle Ford Shale
Density
Pyrite
Salt 2-in Density-Porosity > 0.12 ft3/ft3
2-in Density Porosity
FMI* Formation MicroimagerOrientation North
0 120 240 360
Resistive Conductive
FMI* Formation MicroimagerOrientation North
0 120 240 360
Resistive ConductiveCoal
Siderite
Microporosity
T2 Distribution
Anhydrite and Gypsum
Pyrite
Carbonate
Quartz-Feldspar-Mica
Clay
DensityStandoff
g/cm3–0.9 0.1
SpectroLith* Lithology
lbm/lbm1 0
ft3/ft30.2 0
Standard-ResolutionDensity Porosity
ft3/ft30.2 0
8-in Density Porosity
ft3/ft30.2 0
ELANPlus* Mineralogy
Chlorite
Illite
Montmorillonite
Clay 1
Bound Water
Quartz
Calcite
Oil
Water
Moved Hydrocarbon
Moved Water
V/V1 0
0 29
Pyrite Volume
MeasuredDepth, ft
ft3/ft30 0.07
Kerogen
Pyrite
XX,470
XX,480 Track 3 overlays the standard-resolution density with the 8-in and 2-in curves. The resolution of the 2-in curve is consistent with the enhanced image curve in Track 4. The 2-in-resolution density shows higher porosity (circled) along certain layers that is as much as 5-pu higher than standard resolution. In the same inter-vals, the 50-burst application in Track 5 differentiates very small pores, micropores, and potentially oil-bearing matrix. Compared with the detail provided by the TLD and 50-burst logs, the standard-resolution analysis in Track 6 does not show any bedding but merely an average of the matrix.
1 2 3 4 5 6
Very high-resolution density and 50-burst magnetic resonance reveal laminated pay
Micropore region 3–33 ms
No visible difference seen in standard analysis
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Standard-resolution density porosity
8-in density porosity
2-in density porosity