2012 - Dr Bagus Endar - Shale Gas _edited

GeoSymphony

Shale gas reservoir characterization

Bagus Endar Bachtiar Nurhandoko

ROCK FLUID IMAGING LAB.

GeoSymphony

CONTENTS

Shale gas reservoir system Lesson learned from US Character of Shale Gas Target characterization Role of Rock Physics in shale gas prediction Predicting pressure Total organic content and seismic wave Gas maturity Fracture prediction Rigidity of shale Conclusions References

GeoSymphony

Shale gas

Shale gas is natural gas produced from shale

Shale gas areas are often known as resource plays (as opposed to exploration plays). (Jarvie, 2008)

(U.S. Energy Information Administration (EIA), 2011)

GeoSymphony

Illustration of shale gas compared to other types of gas deposits


GeoSymphony

Shale Resource System: a self contained petroleum system

Around 60% of hydrocarbons expelled into conventional reservoirs

S

SEAL

RESERVOIR SOURCE

GeoSymphony

Lesson learned from US


This fact shows significant production of unconventional gas in US. Therefore, Indonesia has to start in exploring unconventional gas

Unconventional gas produced in US compared by total gas produced in US

GeoSymphony

Character of shale gas reservoir

Shale gas are rich in organic material (0.5% to 25%) and are usually mature petroleum source rocks in the thermogenic gas window, where high heat and pressure have converted petroleum to natural gas. [US DOE, 2009]

Shale gas reservoir are sufficiently brittle and rigid enough to maintain open fractures.

Shale gas is low permeable (especially the primary porosity)

In some areas, shale intervals with high natural gamma radiation are the most productive, as high gamma radiation is often correlated with high organic carbon content

GeoSymphony

Shale matrix under SEM

Courtesy Rock Fluid Imaging Lab.

GeoSymphony

Porosity vs Permeability of Gas shale reservoir

Permeability in mikro Darcy scale !

(Metwally and Chesnokov, 2011)

GeoSymphony

Target of characterization

Target of characterization : 1. Total organic content. Is elastic wave parameter influenced by total

organic content ? 2. Is petroleum source rocks in the thermogenic gas window ?

Heat of shale Pressure (pore pressure and overburden pressure)

3. Fractured zone (shale gas reservoir are sufficiently brittle) 4. Rigidity of shale . Is shale reservoir enough to maintain open

fractures ? 5. High natural gamma radiation are the most productive zone, as high

gamma radiation is often correlated with high organic carbon content

GeoSymphony

Role of Seismic Rock Physics in reservoir characterization

Rock physics relates between Seismic

wave parameter (i.e Velocity, amplitude,

etc.) and Reservoir parameter (i.e:

porosity, clay content, fluid content,

lithology etc.)

ROCK PHYSICS

GeoSymphony

Structure of rock

GeoSymphony








GeoSymphony

Could we measure Total organic content of Shale Gas using Seismic wave ?

Clay rich sample Silica rich sample

Hi TOC correlates with Low Impedance

Zhu et. al., 2011

GeoSymphony

TOC and AVO parameters

Hi TOC tends to the left side of quadrant

Clay rich

Zhu et. al., 2011

GeoSymphony

Seismic Rock Physics Measurement


GeoSymphony

Overburden pressure effect (under gas saturation)

GeoSymphony








GeoSymphony

Quantify source rock maturity and hydrocarbons in place

Petroleum systems modeling assesses exploration risk before drilling, combining your seismic information, well data, and geological knowledge to help you understand the evolution of a sedimentary basin.

Petroleum system modeling sheds light on the source and timing of hydrocarbon generation, migration routes, gas in place, maturation, and hydrocarbon type.

GeoSymphony

Predicting heat of shale

Temperature gradient:

Magnetic : combining Magnetic data, Geochemistry, seismic can result better prediction of shale gas generation

Combining geochemistry and temperature -pressure

(From Clayton, 1991)

GeoSymphony

Predicting Pressure

Overburden pressure history Seismic data -> Burial history Density of shale

Pore Pressure Data input:

seismic prestack, velocity,core-sample Rock Physics analysis Mud log Well log data

Processing: Facies analysis Velocity refinement Statistical-Neural-Network

Pressure history

GeoSymphony

Overburden pressure effect (under gas saturation)


GeoSymphony

Pore pressure effect (under gas saturation)

GeoSymphony

Influence of pore pressure to Seismic wave : some examples

Nurhandoko et. al, 2007

P wave decrease !

GeoSymphony








GeoSymphony

Fracture characterization

Methodology: AVOA (AVO in various azimuth) -> suitable for HTI

fracture ----- very expensive

Fracture modules: Coherency, Maximum Curvature,

AI, Lambda-Mu-Rho which are combined together by fracture parameter from well (Core, Resistivity Scanning) using statistical artificial neural network

VTI

GeoSymphony

Fracture/slate orientation and seismic wave

GeoSymphony

Fracture prediction using Join Rock Physics and Statistical Neural Network

GeoSymphony

Combining Rock Mechanic and Fault to generate Fracture Induced fault map

Rock Mechanic measurement

Fracture induced fault Nurhandoko et.al, 2012

GeoSymphony








GeoSymphony

Predicting rigidity of shale

Data input: Rigid shale (dry) Soft shale (wet) Rock physics measurement

Attributes: AI, Mu, Rho, Lambdac, Poisson, etc. But Mu (Shear Modulus) is solely influenced by matrix

We can combine whole above data for predicting accurately the rigidity of shale using Join statistical Rock Physics and statistical Neural Network

GeoSymphony

References

US Department of Energy, 2009, "Modern shale gas development in the United States", p.17.

_________, U.S. Energy Information Administration (EIA), 2011, Review of Emerging Resources: U.S. Shale Gas and Shale Oil Plays, http://www.eia.gov/analysis/studies/usshalegas/index.cfm#9, released 8 July 2011

Jarvie, D., 2008, Unconventional Shale Resource Plays:Shale-Gas and Shale-Oil Opportunities, NAPE Forum.

Nurhandoko, B. E. B., Susilowati2, Budi, M. L., Siahaan, Ishaq, U. M., Abdillah, W. E., Kusudiharjo, K., Rudiyanto, H., Wiyanto, Y., Sulistyanto, B., 2011, Study Of Seismic Parameter And Avo Responses Of Coal Bed Methane Reservoir Using Rock Physics Physical Modeling, Proceeding HAGI-IAGI Joint Conference.

________, Cokronegoro, R., ikmah, A., Nashruddin, M., Supriyanto, E.B.,2007, Pore pressure effect on seismic wave and AVO parameter, Indonesian Journal of Physics.

________, Ishaq, U.M., 2007, Rock Physics of Anisotrophy and Fracture, IPA

Yu, Z., Liu, e., Martinez, A., Payne, M., Haris, C., 2011, Understanding Geophysical Responses of Shale Gas, The Leading Edge

Metwally, Y., and Chesnokov, E., 2011, Gas shale; relationships between permeability and intrinsic composition, Ext. Abstract SEG 2011 San Antonio.

GeoSymphony

CONCLUSIONS

Strategy of gas shale characterization is following:

Total organic content. Elastic wave parameter can be as a tool for TOC prediction.

Is petroleum source rocks in the thermogenic gas window ?.

Basin modeling by combining geochemistry, seismic, magnetic can be as solution.

Pressure (pore pressure and overburden pressure), anomaly of pressure may be caused by fractured shale

Fractured zone prediction (shale gas reservoir are sufficiently brittle) can be identified by some methods

Prediction the rigidity of shale. Shale reservoir should enough to maintain open fractures, combining geophysics, rock physics and lithology can be as solution for solving this prediction.

GeoSymphony

Thank you

Documents

2012 - Dr Bagus Endar - Shale Gas _edited