Low Resistivity Pay and Heavy Oil_PetroChina_Kickoff

– Resistivity is primary input to water saturation
17
Petrophysical Evaluation Considering Resistivity Anisotropy
– Vertical Resistivity Rv acts in series
0.9m beds
15 cm beds
7.5 cm beds
8
Thin Beds + high resolution electrical images
Depth
GR
Resistivity
Image Log
Murray, D., Alderman, S., Fujii, T. and
Fukuhara, M., 2019, Thin Bed Analysis of Gas
4
Houston and New Orleans Geological Societies
Lowstand basin floor fan complex
Leveed channel complex
Overbank deposits
Overbank
Transgressive marine sands
Pore Fillings Burrowed Sand
Shale Clasts Clay-lined burrows
Pore Linings
Clay Grains
Ash Shards Conductive Pyrite
Small grain size – high Swirr Low formation water salinity
(Synergetic High-Resolution Analysis and Reconstruction for Petrophysical Parameters)
Standard Logs Image Logs
Lithofacies
Convolved logs from Litho-Facies
Geochemical log (ECS) shows increased clay volume. Most water is bound, will not produce
Differences in Bound Water Computation
22
Low Resistivity and Low Contrast Pay
84%
13
Thin Beds
Bohai Bay Example
10 ohm-m line
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Thin Beds
Bohai Bay Example
– FMI Image highlights thin bedded sequences
10 ohm-m line
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Thin Beds
Bohai Bay Example
Shale Clasts Clay-lined burrows
Pore Linings
Clay Grains
Ash Shards Conductive Pyrite
Small grain size – high Swirr Low formation water salinity
3
Low Resistivity and Low Contrast Pay
shale sand intervals in the upper parts of alluvial and distributary channel
Moore, D., 1993, Productive Low Resistivity Well Logs of the
Offshore Gulf of Mexico. New Orleans, Louisiana, USA:
PetroChina Kickoff Meeting
Yang Shiduo and Doug Murray Schlumberger Oilfield Services
1
Outline
Low Resistivity and Low Contrast Pay Heavy Oil – Advances in In-Situ Viscosity Estimation Formation Evaluation in Complex Environments
• Olmos Basin Tight Gas
• Sand B has High GR & Shaly, Sw ~70-80%
Fairhurst, D., Indriati, S., Reynolds, B., Lewis, J., Holcomb, M. and Starr, F., 2019, Advanced Technology Completion Strategies for Marginal Tight Gas Sand Reservoirs: A Production Optimization Case Study in South Texas. SPE 109863
Common Causes
Bed Laminations
Clay Presence
Laminar - shale layers between sand layers
Dispersed - clays throughout the sand, coating sand grains or filling the pore space
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Rt Scanner Result
Rh Rv
Sh from AIT
Sh from RT Scanner
20
Low Resistivity and Low Contrast Pay
Common Causes
Bed Laminations
Clay Presence
Laminar - shale layers between sand layers
Laminar - shale layers between sand layers
Dispersed - clays throughout the sand, coating sand grains or filling the pore space
Structural - grains or nodules in the formation matrix.
Common Dispositional Environments
– Basin floor fan complexes – Deep water levee-channel complexes,
overbank deposits – Transgressive marine sands – Delta front deposits and laminated silt-
Structural - grains or nodules in the formation matrix.
Pore Fillings Burrowed Sand
Shale Clasts Clay-lined burrows
Pore Linings
Clay Grains
Ash Shards Conductive Pyrite
Bearing Sands in the Nankai Trough, 12th
9
Formation Evaluation Symposium of Japan
Image log + synthetic resistivity
Depth
GR
Resistivity
Image Log
10
Thin Bed Analysis Workflow – SHARP
– Volcanics – Metamorphic Rocks Summary
2
Low Resistivity and Low Contrast Pay
Common Causes
Bed Laminations
Clay Presence
Laminar - shale layers between sand layers
Model and Schlumberger Tool Responses Enhanced Logs
+
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Thin Bed Analysis (SHARP)
Standard Logs
Enhanced Logs
12
Reservoir Summation Comparison
Standard Resolution vs SHARP
Small grain size – high Swirr Low formation water salinity
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Small Grain Size - GuangAn Tight Gas
渗透率 饱和度 孔隙度
渗透率 饱和度 孔隙度 泥质含量
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Small Grain Size Texas Tight Gas
5
Thinly Laminated Core
0.2 m
6
Vertical Resolution of Common Logging Tools
70
60 60
Centimeters
50
40 40 40
30 30 30
20
10
5
0.5
0
7
Sonic
Density Wireline
Laterolog
NeutronGamma
Dispersed - clays throughout the sand, coating sand grains or filling the pore space