Oil & Gas Technologies CLO 1 PDF

Oil & Gas Technologies CLO 1 Topics to be covered Part 1: Chemistry of hydrocarbon reserves Origin – How do oil and gas are formed? Migration and accumulation processes of oil and gas Part 2: Chemical composition and different hydrocarbons of oil and gas. Main reservoir hydrocarb...

Oil & Gas Technologies CLO 1 Topics to be covered Part 1: Chemistry of hydrocarbon reserves Origin – How do oil and gas are formed? Migration and accumulation processes of oil and gas Part 2: Chemical composition and different hydrocarbons of oil and gas. Main reservoir hydrocarbons Part 3: Discuss the main properties of reservoir hydrocarbons. Properties of the minerals and rocks containing the reservoir. Part 4: Identify the different reservoir rocks including sandstone, carbonate, limestone etc. Discuss sedimentary rocks characteristics. Part 6: Describe the different types of oil and gas traps.  What Do You Know About Crude petroleum (origin, quality, composition, price,…) ? Refineries (what processes)? Refinery products / by products? Refineries in UAE? The global economy receives almost 80% of its energy subsidies from non-renewable fossil sources: crude oil, gas and coal. 4  What is Energy Source? By definition, " energy sources" must produce more energy than they consume, otherwise they are called "sinks". Crude oil and gas are the most important form of energy we use, making up about 63% of the world energy supply. Different Energy Sources No other energy source equals oil and gas’s intrinsic qualities of extractability, transportability, versatility and cost. 5  Extensive Versus Intensive Properties Intensive/Intrinsic properties are bulk Boiling Point properties, which means they do not depend on the amount of matter that is Density present. These characteristics do not Color depend on the amount of sample, nor Melting Point do they change according to conditions. Hardness Ductility An extensive/Extrinsic property is a Volume property of matter that changes as the specific volume amount of matter changes. Like other Weight physical properties, an extensive property may be observed and Energy measured without any chemical change Chemistry Oil and gas are made of a mixture of different hydrocarbons. A hydrocarbon is a large organic molecule made up of hydrogen atoms attached to a backbone of carbon. Alkanes – They are referred to as saturated hydrocarbons. Alkenes-- These are unsaturated Hydrocarbons i.e. those hydrocarbons that have one or more double bonds between carbon atoms. Alkynes -- Those with one or more triple bonds between carbon atoms are called alkynes. These are mixed with alkanes in petroleum and contribute more carbon dioxide per pound than the saturated hydrocarbons. Chemistry Cycloalkanes – Any hydrocarbon containing one or more ring structures Aromatic Hydrocarbons – This class of molecules has specialized ring structures where bonds between carbon atoms are an intermediate between single and double bonds. Chemistry of crude petroleum When crude petroleum is extracted from the earth it may be a mixture of hydrocarbons in solid, liquid and gas states. Short chain hydrocarbons like methane are gases. Medium chain hydrocarbons like paraffin are liquids. Long chain hydrocarbons like bitumen are solids. Hydrocarbons containing up to four carbon atoms are usually gases, those with 5 to 19 carbon atoms are usually liquids and those with 20 or more are solids. Chemistry Hydrocarbons containing between 6 and 10 carbon molecules are the top components of most fuels, regardless of whether they are alkanes, alkenes, or cyclic.  What is Crude Oil? Crude oils are in liquid form containing complex mixtures of many different hydrocarbon compounds. Crude oils vary in appearance and composition from one oil field to another. An "average" crude oil sample contains about 84% C, 14% H, 1- 3% S and less than 1% each of N, O, metals, salts and other elements. Crude oils are generally classified as paraffinic, naphthenic or aromatic, based on the predominant proportion of hydrocarbon molecules. 12  Classification of Crude Oils The oil industry classifies "crude"  By the location of its origin (e.g., "West Texas Intermediate, WTI" or "Brent") and  Often by its relative weight or viscosity ("light", "intermediate" or "heavy");  Refiners may also refer it as "sweet," which means it contains relatively little sulphur or as "sour," which means it contains substantial amounts of sulphur and requires more refining in order to meet current product specifications. Each crude oil has unique molecular characteristics which are understood by the use of crude oil sample analysis in petroleum laboratories. 13  Classification of Crude Oils (continued) These references are known as Crude oil benchmarks:  Brent Crude, comprising 15 oils from fields in the Brent in North Sea.  West Texas Intermediate (WTI) for North American oil.  Dubai, used as benchmark for Middle East oil flowing to the Asia-Pacific region.  Tapis (from Malaysia, used as a reference for light Far East oil).  Minas (from Indonesia, used as a reference for heavy Far East oil).  The OPEC Reference Basket, a weighted average of oil blends from various OPEC countries. 14 Hydrocarbons in Crude Oils Composition of Petroleum 15  Basics of Hydrocarbon Chemistry Crude oil is a mixture of hydrocarbon molecules, which are organic compounds of carbon and hydrogen atoms that may include from one to 60 carbon atoms. The properties of hydrocarbons depend on the number and arrangement of the carbon and hydrogen atoms in the molecules. Hydrocarbons containing up to four carbon atoms are usually gases, those with 5 to 19 carbon atoms are usually liquids and those with 20 or more are solids. Main Hydrocarbons in Crude Oils: Paraffins, Aromatics, Naphthenes (Cycloparaffins), Other Hydrocarbons (Alkenes, and Alkynes). 16  Paraffins The paraffinic series of hydrocarbon compounds found in crude oil have the general formula CnH2n+2 and can be either straight chains (normal) or branched chains (isomers) of carbon atoms. Examples of straight-chain molecules are methane, ethane, propane and butane (gases containing from one to four carbon atoms) and pentane and hexane (liquids with five to six carbon atoms). The Simplest Paraffin – Methane CH4 n Butane and Isobutane - C4H10 17  Aromatics Aromatics are unsaturated ring-type (cyclic) compounds which react readily because they have carbon atoms that are deficient in hydrogen. All aromatics have at least one benzene ring as part of their molecular structure. Toluene (C7H8) Benzene (C6H6) Napthalene (C10H8) 18  Naphthenes Naphthenes are saturated hydrocarbon groupings with the general formula CnH2n, arranged in the form of closed rings (cyclic) and found in all fractions of crude oil except the very lightest. 19 PHYSICAL PROPERTIES OF HYDROCARBONS Color Specific gravity is the ratio of the density of a substance to the density of a reference Odor substance; ٧ Density Specific Gravity The flash point is the lowest temperature at which a substance vaporizes into a gas, which can be Boiling Point ignited with the introduction of an external source of fire. Freezing Point Flash Point Units – centipoises (μ, cp) Viscosity Strongly temperature dependent PHYSICAL PROPERTIES OF HYDROCARBONS Refractive Index A property of a material that changes the speed of light, ; It is calculated as the ratio of the velocity of light in vacuum to its velocity in a specified medium. ˚ API gravity = 141.5 - 131.5 ٧ ٧ = specific gravity  The Origin of Petroleum Oil & Gas; Theories https://www.youtube.com/watch?v=pvH-h7TzSsE The Organic Theory https://www.sciencelearn.org.nz/videos/800-oil-formation According to the this theory, oil & gas originates from animals and plants where beds of silt (containing tiny organisms), mud and sand were buried deep beneath the earth. Geologists believe that high heat and pressure, bacteria, chemical reactions and other forces transformed the organic remains into oil and gas. The Inorganic Theory Hydrocarbons are formed by combination of carbon and hydrogen in the earth rocks due to the influence of high temperature and pressure 22 Origin: Plankton Plant Animal Most of the world’s oil plankton plankton and gas is made up of would fit on a pinhead! 10,000 of these bugs the fossil remains of microscopic marine plants and animals. That’s why oil and gas are often referred to as fossil fuels. Some oil and gas may have also originated from the Most oil and gas starts life as microscopic plants and animals remains of land plants. that live in the ocean. Origin: Black Shale When plankton dies it slowly settles to the sea bed where it forms an organic mush. However, if there is little or no oxygen in the water then animals can’t survive and the organic mush accumulates. Where sediment contains more than 5% organic matter, it eventually forms a rock known as a Black Shale Origin: Cooking As Black Shale is buried, it is heated. Organic matter is first changed by the increase in temperature into kerogen, which is a solid form of hydrocarbon. At temperatures of around 30°C, a solid, sticky bitumen is produced. Around 90°C, it is changed into a liquid state, which we call oil Around 150°C, it is changed into a gas A rock that has produced oil and gas in this way is known as a Source Rock  Types of Rocks The three main types, or classes, of rock are sedimentary, metamorphic, and igneous and the differences among them have to do with how they are formed. Sedimentary Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock. Examples of this rock type include conglomerate and limestone. Metamorphic Metamorphic rocks are formed under the surface of the earth from the metamorphosis (change) that occurs due to intense heat and pressure (squeezing). The rocks that result from these processes often have ribbon like layers and may have shiny crystals. Examples of this rock type include marble. Igneous Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens. Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava). When lava cools very quickly, no crystals form and the rock looks shiny and glasslike. Examples of this rock type include basalt. Geological Conditions for Oil and Gas Formation Most oil and gas accumulates in sedimentary rocks. Sedimentary rocks (formed by sediment from surrounding rock structures and water) are one of three main rock groups (others are igneous and metamorphic rocks). Sedimentary rocks covers 75-80% of the Earth's land area and include common types such as chalk, limestone, dolomite, sandstone, conglomerate and shale. 28 Rock Cycle https://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle.html 29  Sedimentary Rocks Chalk is a soft, white, porous Limestone is a sedimentary rock Dolomite: is a sedimentary carbonate sedimentary rock, a form of composed largely of the mineral rock and a mineral, both composed of limestone composed of the calcite (calcium carbonate: calcium magnesium carbonate mineral calcite CaCO3) CaMg(CO3)2 found in crystals. Sandstone is a sedimentary rock Conglomerate is a rock consisting Shale is a fine-grained sedimentary composed mainly of sand-size of individual stones that have rock whose original constituents mineral or rock grains. become cemented together were clay minerals or muds. 30  Properties of sedimentary rocks Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates Limestone is a sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO3) Dolomite: is a sedimentary carbonate rock and a mineral. Dolomites are usually formed by recrystallization of original aragonite or calcite crystals in sediments. Magnesium in the pore fluids replace some of the calcium, forming a Mg-Ca carbonate structure.  Properties of sedimentary rocks Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. Like sand, sandstone may be any color, but the most common colors are brown, yellow, red, gray and white. A conglomerate is a rock consisting of individual stones that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments. Shale is a fine-grained sedimentary rock whose original constituents were clay minerals or muds.  Reservoir Rocks A petroleum reservoir, or oil and gas reservoir, is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. The naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability. According to Society of Petroleum Engineers Glossary, a reservoir rock is a rock containing porosity, permeability, sufficient hydrocarbon accumulation and a sealing mechanism to form a reservoir from which commercial flows of hydrocarbons can be produced. 33  Reservoir Rocks Porosity and permeability are important factors in reservoir formation. Porosity The porosity of a rock is a measure of the storage capacity (pore volume)that is capable of holding fluids. Quantitatively, the porosity is the ratio of the pore volume to the total volume (bulk volume). (e.g. Shale is less porous and carbonate is more porous).  Permeability is an intrinsic property of a material that determines how easily a fluid can pass through it. In the petroleum industry, the Darcy (D) is the standard unit of permeability, (a rock is permeable when the pores are connected).  Porosity and Permeability Just as with porosity, the packing, shape, and sorting of granular materials control their permeability. Although a rock may be highly porous, if the voids are not interconnected, then fluids within the closed, isolated pores cannot move. https://www.youtube.com/watch?v=8YHsxXEVB1M 35 https://www.youtube.com/watch?v=5uyPY96jtxU Reservoir Rocks (erosion and deformation) For a rock to be an effective reservoir, it must contain adequate porosity and permeability that is properly sealed against erosion and tectonic (movement) destruction. Many reservoirs and traps have been generated and eliminated by erosion and deformation. These are called dead oil. 36 Rock Type Distribution in the Earth Crust and Oil and Gas Production by Rock Type Carbonates 21% Class of sedimentary rocks composed Sandstone 37% primarily of carbonate Shale 42% minerals. Two major types are: Distribution of rock types 1) Limestone (CaCO3) 2) Dolomite [CaMg(CO3)2] Miscellaneous 2.5% Sandstone 36% Carbonates 61.5% (more pores) Production by rock types 37  https://www.youtube.com/watch?v=iCTDSuDcyPw Migration https://www.youtube.com/watch?v=nPOq7zUojqg Hot oil and gas is less dense than the source rock in which it occurs Oil and gas migrate upwards up through the rock in much the same way that the air bubbles of an underwater diver rise to the surface The rising oil and gas eventually gets trapped in pockets in the rock called reservoirs Rising oil  Migration of Crude Oil Even though shale is relatively impermeable, oil is created in its pores. As tectonic forces moves the petroleum forming rocks out of there birthplace, great pressures from overlying formations squeeze the petroleum out of the relatively impermeable shale into cracks and into more permeable formations such as sandstone (i.e. carbonate rocks). 39  Summary (Oil Migration) Original Organic Matter Kerogen Mature Crude Oil Kerogen Graphite Methane Losing Hydrogen Gaining Hydrogen 40  Oil and Gas Traps If the rock containing the oil is very porous and very permeable, petroleum will escape. Something must stop the oil from escaping and migrating. A trap is any combination of physical factors that promotes accumulation and retention Impermeable of the petroleum in one location. Some rocks are permeable and allow oil and gas to freely pass through them but other rocks are impermeable and block the upward passage of oil and gas. This is one type of Oil Trap. Permeable 41  Types of Traps Structural traps: These traps are types that form as a result of some structural deformation - a bend or dip - of rock. These traps take on several forms and shapes as a result of different types of deformation. Shapes of dome, antiklines and faults are common structures. Fault related features also may be classified as structural traps if closure is present.  Anticline Traps are formed by a folding of rock under pressure and compaction. Specifically, a sandstone bed covered with low permeability shale is folded into a trap that contains petroleum products. Hydrocarbons are trapped in the peak of this fold  Fault Traps are formed when reservoir rock is split along a fault line. Between the walls of the split reservoir, clay traps oil and prevents it from leaving the trap 43  Salt Dome traps are formed as a result of below ground salt - which is less dense than the rock above it - moving upwards slowly and deforming the rock along the way. The process of this salt deforming rock is known as salt tectonics. Oil and gas that flows through the reservoir rock will come to rest when it reaches the salt dome and is then trapped Impermeable  Types of Traps Stratigraphic traps are formed when other beds seal a reservoir bed or when the permeability changes within the reservoir bed itself. There are two main types  Primary stratigraphic traps result from changes that develop during the sedimentation process. These are structural changes that arise as a result of discontinuous deposition of sediment.  Secondary stratigraphic traps result from changes that develop after sedimentation has occurred. These changes can involve changes in porosity of the rock that lead to formation of a cap-like rock. 45 https://www.youtube.com/watch?v=_PDOD_FEnNk https://www.youtube.com/watch?v=_PDOD_FEnNk  Exploration Methods Exploration was once a matter of good luck and guess work. Most successful method was to drill near an oil seeps (where oil is actually present on the surface). Now it uses many techniques and scientific principles. Today, surface and subsurface study is the leading technology in discovering oil and gas. Aerial and satellite images and other instrumentation are used to gather information that helps determine where to drill. 47  Exploration Methods (continued) Then specialist examine the rock fragments and core samples brought up while drilling the well and running special tools into the hole to get more information about the formation and possible oil or gas traps. Finally examining, correlating and interpreting the information and the data makes it possible for the oil companies to accurately locate structures that may contain hydrocarbon and if the hydrocarbons are worth exploiting. 48  Exploration Methods Summary Exploration methods include: 1. Surface geological studies 2. Oil and gas seeps. 3. Geophysical surveys (e.g. seismic surveys) 4. Reservoir development tools 49  Geophysical, Geochemical, and Direct Exploration Techniques Geophysical Exploration Techniques Seismic reflection and refraction, gravity surveys magnetic survey using proton magnetometer electrical resistivity Geochemical Exploration Methods Satellite images soil sampling stream sampling Direct Exploration Methods Drilling Exploration and Production: Seismic Surveys Drill here! Seismic surveys are used to locate likely rock structures underground in which oil and gas might be found. Shock waves are fired into the ground. These bounce off layers of rock and reveal any structural domes that might contain oil.  Seismic Reflection This technique is used extensively in oil exploration as well as for metal ores. The seismic reflection method works by bouncing sound waves off boundaries between different types of rock. The reflections recorded are plotted as dark lines on a seismic section. This method can be implemented both on land and at sea. It shows up rocks with contrasting densities so ores show up well as well as less dense rocks like salt. Mapping If rocks are exposed at the surface then mapping them can give a clear indication of the geology not only on the surface but also underground. You may be able to work out an underground cross section. Digital images of the subsurface layers and faulted structures are created. Even details of past environments, such as river channels on ancient flood plains or sediments on the former deep-ocean floor, can be identified and mapped Exploration and Production: Drilling the well Once an oil or gas prospect has been identified, a hole is drilled to assess the potential. The cost of drilling is very great. On an offshore rig, it may cost $20,000 for each metre drilled. A company incurs vast losses for every “dry hole” drilled. Direct exploration methods Drilling  Drilling in an area is often the only way of being absolutely sure what is underground.  The geochemical and geophysical methods will give a clue.  Analysing the samples and noting the depths at which rocks occur can help in deciding whether an ore is worth mining or not.  Drilling is only used in areas that have been selected as "targets" from geological, geophysical and/or geochemical methods. Rotary drilling Rotary drilling is a technique which employs a rotating drill bit that grinds/pulverizes the soil/rock as the drill bit advances Then it uses a medium (such as compressed air, water, or drilling mud) to transport the drill cuttings up to the ground surface. Rotary drilling is most commonly associated with water and oil well drilling  Types of Drilling Conventional Drilling Conventional wells are drilled vertically from the surface straight down to the pay zone. This is the traditional and still common type of drilling. Horizontal Drilling Using technologies such as bottom driven bits, drillers are able to execute a sharp turn and drill horizontally along a thin pay zone. Slant Drilling Drilling at an angle from perpendicular (commonly 30° to 45°). This approach minimizes surface environmental disturbance. Directional Drilling Drilling has advanced from slant and horizontal drilling to drilling that can change direction and depth several times in one well bore.  Left to right; Conventional, Slang, horizontal 58  Well Logs and Sample Logs Reservoir Development Tools When a surface and subsurface information of a formation indicates a strong possibility of hydrocarbon existence, an oil company may then drill an exploratory well or wells. As the drilling progresses, underground rocks are then tested by means of core sampling and well logs. The gathered data determines whether the reservoir has enough oil or gas to justify completing the exploration and then production. 59  Reservoir Development Tools (continued) Well logs are records that give information about the formation through which a well has been drilled. The log gives the geophysical and other information of a well per depth. 60  Types of Well Logs 1. Well Logs: Driller’s log Wireline log (Electrical log, Nuclear log, Acoustic log)  Electrical log (resistivity, induction) 2. Sample logs: Core Samples Cutting Sample 61  1. Well Logs Driller’s log It’s the most common log where the log contains information about the kind of rocks and fluids encountered at different depths. It gives also gives information when the formation is altered from soft to hard rock. It gives an idea of how long it takes to drill the well (for future drilling purposes). Gives other formation issues encountered during drilling. 62  1. Well Logs (continued) Wireline log A wireline is a metal cable (line) that run through the well hole with several tools attached to it. Each tool takes a different measurement. Each measurement gives an indirect information about the formation down the well. Wireline logging often involves complex calculations and interpretations of the data provided from the tool. Oil service companies (e.g. Schlumberger, Baker Atlas, Halliburton) uses the information to decide if the oil or gas in the well is economically feasible. 63  1. Well Logs – Wireline logs (continued) There are different types of wireline logs: Electrical Logs, Nuclear Logs, Acoustic Logs. A) Electrical Logs Electric logging measures the formation resistivity or conductivity and the spontaneous potential. Induction Log: records conductivity (weak current) that flows in the rocks. It gives an idea about the thickness and boundary of each layer in the borehole (called spontaneous potential log i.e. SP log). 64  1. Well Logs – Wireline logs (continued) Resistivity Log: records resistance in the borehole (hydrocarbons do not conduct electricity while all waters do). Both the brine in the pore space and the water bound to the clay in formation rocks conduct electric current. The measured conductivity reflects the presence of brine in the rock and water bound to clay minerals. Formations with very low porosity or whose porosity is occupied by nonconductive oil and gas are identified by high resistivity segments in electric logs. 65  1. Well Logs – Wireline logs (continued) B) Nuclear Logs Several types of radioactivity logs measure the natural radioactivity of the formation, while others emit radioactive particles and measure the response from the formation. Gamma ray log:  Measures radioactivity to determine what type of rocks are present in the well. For example shale emits more radioactive elements than sandstone.  In general, K, U and Th are the primary contributors to natural radioactivity in the sedimentary formations. These elements primarily occur in clay minerals. 66  1. Well Logs – Wireline logs (continued) Neutron log:  The tool sends atomic particles (neutrons) through the formation. When the neutrons collide with hydrogen, the hydrogen slows them down.  When the detector records slow neutrons, it means that there more hydrogen is present (i.e. maybe more hydrocarbons than water). 67  1. Well Logs – Wireline logs (continued) C) Acoustic Logs It gives information about the density of the rocks (how dense the rock is). The acoustic or sonic log records how fast sound travels through a rock. The speed of sound traveled depends on how dense a formation is and how much fluid it contains. Example: shale is less porous therefore the sound will travel faster and you will get a high acoustic signal back. (e.g. of signal on the board) 68  2. Sample Logs Sample logs:  Core Samples  Cutting Sample Core samples  A core is a cylindrical column of rock that shows the sequence of rocks as they appear within the earth.  It provides the most accurate information about the underground formation about porosity, permeability, composition, fluid content and geological age. 69  2. Sample Logs (continued) Cutting samples  As a regular bit drills a hole, it breaks up the rock into pieces called cuttings. The cuttings flow out of the hole where geologists can use them to analyze the rock being drilled.  Since cuttings are fragments of rocks and do not form a continuous sample like a core, they are not as useful cores are to the geologists.  Cuttings may not all come from the bottom of the hole but may include pieces of formations that have sloughed off closer to the surface.  Even with these limitations, however, cuttings can provide useful data and are regularly examined during drilling. 70 Exploration and Production: Primary and Enhanced Recovery Although oil and gas are less dense than water and naturally rise up a well to the surface, in reality only 40- 50% of the total will do so. To enhance recovery, a hole is drilled adjacent to the well and steam is pumped down. The hot water helps to push the oil out of the rock and up into the well. Exploration and Production: Enhanced Recovery Primary Recovery - 20 to 30% of oil in reservoir.  Least expensive  Uses natural pressure supplied by: o Water, Gas cap, Solution gas Secondary Recovery (Enhanced Oil Recovery) increases production to 50-60% Water injection, gas re-injection 72