Petrophysics Of Organic Clay

भारतीय प्रौद्योगिकी संस्थान (भारतीय खनन विद्यापीठ), धनबाद INDIAN INSTITUTE OF TECHNOLOGY (ISM), DHANBAD पेट्रोलियम अलभयांत्रिकी विभाि Department of Petroleum Engineering

Term Presentation on; ‘Petrophysics of Organics, Clay, Sand and Shale’

PRITISH BARMAN 1ST Year, M.Tech (2016-18)

Content  OBJECTIVE  INTRODUCTION  Petrophysics of ORGANICS  CARBONATES  COAL

 Petrophysics of CLAY  Petrophysics of SANDS  Petrophysics of SHALES  Data Acquisition  Case Study

 CONCLUSION  REFERENCES

Objective PETROPHYSICS Definition Petrophysical Properties Φ, k, Sw, F, Pc, Wettability

Measurement Techniques W/Log, Core, Well Test, MWD/LWD

Rock Types Clastic / Non-Clastic

Introduction to Petrophysics  (rock physics) - branch of applied geology relating to the study of reservoir and cap rock properties and their interactions with fluids (gases, hydrocarbon, and aqueous solutions)  based on fundamental methods of physics, chemistry and mathematics  mineralogy and geology  Rock Classification  Sedimentary, Igneous and Metamorphic  Clastic / Non-Clastic

Petrophysical Properties  Porosity, Φ

:

 Permeability, k

Absolute & Effective :

Absolute & Relative

 Water Saturation:

Initial, Connate.

 Formation Factor, F :

Archie’s Equation

 Capillary Pressure, Pc :

Fluid Displacement

 Wettability

Drainage and Imbibition

:

Organics  Organic Matter Origin

Carbonate: lime (Cao)-secreting animals, plants, and bacteria live in the shallow water.

 Precipitation of Calcite

Coal: thermal maturity of plant matter.  Overburden Pressure and Time  Methane is generated, Adsorbed in Cleat.

Carbonate Rock  Carbonate rocks are a class of sedimentary rocks  composed primarily of carbonate minerals.

 major types are  Limestone: calcite or aragonite (different crystal forms of CaCO3)  Dolostone: composed of the mineral dolomite (CaMg(CO3)2) PROCESS

FAVORABLE EFFECTS

UNFAVORABLE EFFECTS

Leaching

Increase ¢ & K

-

Dolomitization

Increase K

Can also Decrease ¢ & K

Fracturing Joints Breccia

Increase K

Increase Channeling

Recrystallization

May Increase

Decrease ¢ & K

Cementation By Calcite Anhydrite Pyro-bitumen Silica

-

Decrease ¢ & K

Decrease Pore Size & K

Coal  Coal is a chemically complex organic aggregate of Carbon  Combustible solid consisting of a mixture of altered plant remains.  Organic matter constitutes more than 50% of coal by weight and more than 70% by volume.  Coals are described and classified by differences in composition (type), purity (grade), and maturity (rank).  Main Interest of Coal to the Hydro-Carbon Industry is Coal Seam Gas/ or CBM.  Natural dual porosity system – Face and Butt Cleat  Permeability 0.1–50 Md.

Fig. Coal Cleat System

Clay  Claystone is a sedimentary rock made of more than 67 percent clay-size (<1/256 millimeter) particles  Types of Clay: Swelling and Non-Swelling  Swelling Clay: Smectite  Non-Swelling Clay: Keolonite, Illite type.

Fig. SEM images of a smectite-rich sandstone.

Sand  Particles are relatively larger with grains between 1 to 1/16 mm.  Average Porosity in between 10-30 %  Permeability between 15-300 mD

 With continued diagenesis, large amounts of cement would develop, reducing the pore volume.

Fig. Microscopic view of a sand face

Fig . Common sandstone textures include point contacts, cements, and micro-fractures. These microstructures determine the properties of the rock on a whole.

Shale  Shales exhibit low very low permeability in the range of 1µD to 1mD. The porosity however can be as high as 20%.  Organic Content of the Shale is characteristic of the environment of deposition.  Quality of the organic matter, Kerogen is essential in the generation of hydrocarbon.

Fig. . Thin-section image of an organic-rich siltstone

DATA ACQUISITION

CASE STUDY: Bombay Offshore  It came into existence during Upper Cretaceous time  Predominantly Carbonate Reservoir Rock  Main producing zone, L-III, consisting of many sedimentary cycles.  Capped by a post-middle Miocene shale  Heterogeneity is high

 85% Wells on Gas Lift  Average Water Cut 65 % Petrophysical Property

Value Range

Porosity

15-35 %

Permeability

10mD to 1D

Conclusion  The Petrophysics - function of the environmental conditions prevalent during the time of deposition.  Rocks are classified primarily with respect to their average grain size, Clay <Shale < Sand  Carbonate rocks are formed by the secretion of marine animals and plants, and often by precipitation of calcite.  The main Petrophysical properties of importance to the hydrocarbon exploration include  porosity,  permeability,  water saturation,  formation resistivity factor,  capillary pressure, and  wettability.

References  [1] Leonid Buryakovsky, George V. Chilingar, Herman H. Rieke, and Sanghee Shin, 2012 –Fundamentals of the Petrophysics of Oil and Gas Reservoirs.  [2] Djebbar Tiab & Erle C. Donaldson, Third Edition 2012 –Petrophysics, Theory and Practice of Measuring Reservoir Rock and Fluid Transport Properties  [3] Daniel Jardine and John William Wilshart, Esso Resources Canada Limited, SPE 10010 Society of Petroleum Engineers, -Carbonate Reservoir Description

 [4] By C. Jenkins, DeGolyer and MacNaughton, D. Freyder, Freyder Enterprises Inc., J. Smith, Great Plains Energy, and G. Starley, Devon Energy Corp. Vol6_Page_247 –Petroleum Engineering Handbook.  [5] Meng Lu, SPE and Luke D. Connell, SPE, Division of Earth Science and Resource Engineering, CSIRO, Australia, SPE 133100 - Dual Porosity Processes In Coal Seam Reservoirs