董明哲--渗流物理--Topic 1 Definitions

8 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
1.4 Formation of Gas and Oil Traps Origin of Petroleum There exist two different theories of the origin of petroleum: the organic theory and the inorganic theory. 1) Organic theory Oil and gas formed from the remains of plants and animals. The rich mixture of sediment (grains of silt, sand, and mud) and organic material deposited in the bottom of shallow seas. High heat, pressure, bacteria, chemical reactions transformed the organic remains into oil and gas. 2) Inorganic theory Inorganic theory (the early 1800s) holds that petroleum is either left over from the formation of the solar system or was formed later deep within the earth.
3 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
1.3 Sedimentary Rocks Source and reservoir rocks for gas and oil. 99.9% of oil and gas were founded in sedimentary rocks. Important to study of petrophysics and reservoir engineering. Three types of sediments: 1) Clastic sediments – deposited as whole particles, such as boulders, sand grains, mud particles. 2) Organic sediments – formed biologically such as shells. 3) Crystalline sediments – formed by the precipitation of salt. Formation of Sedimentary Rocks: 1) Cementation – salts precipitate out of subsurface water to form coatings on the sediment grains and bridge the loose sediment grains together. 2) Compaction – sediments are solidified under high pressure exerted by overlying rocks.
Oil
Grain
Water
Cements
Fig来自百度文库re 1.2 Parts of sedimentary rock (clastic)
5 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
Two most common petroleum reservoir rocks Sandstones ― rocks made from small grains of the minerals quartz and feldspar Carbonates ― composed primarily of carbonate minerals. o Limestone (CaCO3) o Dolomite (CaMg(CO3)2) Ground water Ground water ― water below the surface in pores of sedimentary rocks. Fresh water – salt content ~0-1 ppt (parts per thousand) Brines – (35-300 ppt) Formation water (Connate water) – subsurface water that has been out of contact with the atmosphere for a long time. Originally trapped in the sediments when they were deposited. Bottom water – aquifer below oil formation Water table – boundary between the dry layer and water layer
6 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
Rock properties Porosity – the percentage of the total pore volume of the rock. Effective porosity – a measure of the void space that is filled by recoverable oil or gas. Table 1.1 Range of porosity values Porosity 0–5 5 – 10 10 – 15 15 – 20 20+ Qualitative evaluation negligible poor fair good very good
1 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
Immiscible displacement: unsteady two-phase flow. Miscible displacement: mixing process in porous media during displacement. Application of porous media flow in reservoir engineering: relationships between oil recovery and capillary number (ratio of capillary force to viscous force).
7 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
Permeability – the property of a medium of allowing fluids to pass through it. Table 1.2 Range of permeability values Permeability (mD) < 1.0 – 15 15 – 50 50 – 250 250 – 1000 > 1000 Qualitative description poor or fair moderate good very good excellent
1. Introduction to Petroleum Geology and Reservoir Rocks Petroleum geology concerned with rocks containing oil and gas Oil reservoir is rock formation containing oil and gas in its pore space 1.1 Rocks and Minerals Minerals ― mixtures of one or more elements (stony chemical compounds) Examples ― quartz (SiO2 ) and calcite (CaCO3) Rocks ― aggregates of small grains or minerals Examples: Granite ― composed of quartz, feldspar, hornblende, and biotite Limestone ― body of calcite.
2 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
1.2 Types of Rocks Igneous Rocks ― Plutonic rocks and lavas Sedimentary rocks ― gradually formed by the deposition of sediments Metamorphic rocks ― re-crystallized from igneous rocks under high temperature and pressure.
Introduction to Flow in Porous Media
Mingzhe Dong
Topic 1 Flow through Porous Media
Introduction Porous materials seen and used everywhere. Definition of porous material differs in different studies. Study of porous media flow concerned with porous materials: o Solid or semisolid; o Containing pores or voids; o Permeable to fluids. You will learn from this course: Pore structure parameters: porosity, permeability, specific surface area, pore-size distribution, formation resistivity factor. Capillarity in porous media: capillary forces, two displacement processes (imbibition and drainage). Wettability in porous media: wettability, measurements, contact angle hysteresis. Steady single phase flow: different forms of Darcy’s law for three types of fluids in linear and radial flow. Steady–state multiphase flow in porous media: capillary pressure curves and relative permeability curves.
Sedimentary Rock
Compaction cementation
Sediments Erosion weathering
Heat pressure
Igneous Rock
Cooling crystallization Magma
Heat Melting
Metamorphic Rock
Figure 1.1 The rock cycle (after Dyke, 1997)
4 2014 Topic 1
Introduction to Flow in Porous Media
Mingzhe Dong
Three parts of the Sedimentary Rocks (clastic) 1) Sediment grains – frame or matrix 2) Natural cements coating and bonding the grains together 3) Pore space – filled with fluids (oil, water, gas)