Oil & Gas Industry and Sustainable Development PDB1012 PDF

PDB1012 Introduction to Oil & Gas Industry and Sustainable Development TOPIC 2 : Introduction to Oil & Gas Exploration Lecture Outline Origin of Petroleum o Rock Cycle o Sedimentary basins o Conventional and unconventional reservoirs Petroleum System o So...

PDB1012 Introduction to Oil & Gas Industry and Sustainable Development TOPIC 2 : Introduction to Oil & Gas Exploration Lecture Outline Origin of Petroleum o Rock Cycle o Sedimentary basins o Conventional and unconventional reservoirs Petroleum System o Source rock o Reservoir rock o Seal Rock o Overburden rock Exploration Techniques o Magnetic techniques o Gravimetric survey o Seismic method Exploration and Appraisal Well Origin of Petroleum o Rock cycle o Sedimentary basins o Conventional and unconventional reservoirs Origin of Petroleum ROCK CYCLE o Source : http://www.cotf.edu/ete/mod ules/msese/earthsysflr/rock.h tml Origin of Petroleum ROCK CYCLE The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. When it pours out on Earth's surface, magma is called lava. Yes, the same liquid rock matter that you see coming out of volcanoes. Origin of Petroleum ROCK CYCLE On Earth's surface, wind and water can break rock into pieces. They can also carry rock pieces to another place. Usually, the rock pieces, called sediments, drop from the wind or water to make a layer. The layer can be buried under other layers of sediments. After a long time the sediments can be cemented together to make sedimentary rock. In this way, igneous rock can become sedimentary rock. All rock can be heated. But where does the heat come from? Inside Earth there is heat from pressure and friction. There is also heat from radioactive decay (the process that gives us nuclear power plants that make electricity). Origin of Petroleum ROCK CYCLE So, what does the heat do to the rock? It bakes the rock. Baked rock does not melt, but it does change. It forms crystals. If it has crystals already, it forms larger crystals. Because this rock changes, it is called metamorphic. Metamorphosis can occur in rock when they are heated to 300 to 700 degrees Celsius. When Earth's tectonic plates move around, they produce heat. When they collide, they build mountains and metamorphose the rock. The rock cycle continues. Mountains made of metamorphic rocks can be broken up and washed away by streams. New sediments from these mountains can make new sedimentary rock. The rock cycle never stops. Origin of Petroleum World Sedimentary Basins Deep water Shallow water - offshore Shallow water - onshore Cratonic areas Origin of Petroleum SEDIMENTARY BASINS The official definition of a sedimentary basin is: a low area in the Earth’s crust, of tectonic origin, in which sediments accumulate. Sedimentary basins range in size from as small as hundreds of meters to large parts of ocean basins. The essential element of the concept is tectonic creation of relief, to provide both a source of sediment and a relatively low place for the deposition of that sediment. Source : https://ocw.mit.edu/courses/earth-atmospheric-and-planetary-sciences/12-110-sedimentary-geology- spring-2007/lecture-notes/ch11.pdf A depression in the crust of the Earth formed by plate tectonic activity in which sediments accumulate. Continued deposition can cause further depression or subsidence. Sedimentary basins, or simply basins, vary from bowl-shaped to elongated troughs. If rich hydrocarbon source rocks occur in combination with appropriate depth and duration of burial, hydrocarbon generation can occur within the basin. Source : http://www.glossary.oilfield.slb.com/Terms/s/sedimentary_basin.aspx Origin of Petroleum CONVENTIONAL AND UNCONVENTIONAL RESERVOIRS o Source : https://www.croftsystems.net/oil-gas-blog/conventional-vs.- unconventional  Origin of Petroleum CONVENTIONAL RESERVOIRS Conventional oil and gas is simply known as the traditional way to drill for raw natural gas, crude oil, and petroleum. After a well is drilled, oil and gas is extracted by the natural pressure from the wells and pumping operations. Over time, the well may decrease in production. At this time, a conventional well will use an artificial lift or water and gas injections to help increase production. After production gets to a point where the profits of oil are not enough to cover expenses, the well will usually stop production. If methods beyond an artificial lift or classic methods are used to increase production, then it would be classified at unconventional oil.  Origin of Petroleum UNCONVENTIONAL RESERVOIRS Sometimes unconventional drilling methods are used due to increasing scarcity of retrieving oil and gas using conventional methods. Not always, is the oil and gas available to be retrieved by drilling and pressure naturally allowing the flow of gas. In this case, unconventional drilling comes in handy. Unconventional is a method that allows to drill down, drill horizontally, and fracking occurs. This allows oil and gas to be flowing from tight sands that we normally could not retrieve with conventional methods of drilling. Petroleum System o Source rock o Reservoir rock o Seal rock o Overburden rock Petroleum System SOURCE ROCK o A rock rich in organic matter which, if heated sufficiently, will generate oil or gas. Typical source rocks, usually shales or limestones, contain about 1% organic matter and at least 0.5% total organic carbon (TOC), although a rich source rock might have as much as 10% organic matter. o Rocks of marine origin tend to be oil-prone, whereas terrestrial source rocks (such as coal) tend to be gas-prone. Preservation of organic matter without degradation is critical to creating a good source rock, and necessary for a complete petroleum system. o Under the right conditions, source rocks may also be reservoir rocks, as in the case of shale gas reservoirs. Petroleum System Source : http://spe-sc.ft.ugm.ac.id/w/source-rock-and-kerogen/ Petroleum System RESERVOIR ROCK o A reservoir rock is a place that oil migrates to and is held underground. A sandstone has plenty of room inside itself to trap oil, just like a sponge has room inside of itself to soak up spills in your kitchen. o It is for this reason that sandstones are the most common reservoir rocks. Limestones and dolostones, some of which are the skeletal remains of ancient coral reefs, are other examples of reservoir rocks. Petroleum System RESERVOIR ROCK o Here we see what a reservoir rock would look like through a magnifying lens. The yellow objects represent sand grains that are packed together. o Notice, however, the purple areas between the sand grains. These areas (also known as "pore spaces") are where the oil fits into the rock. In a very "porous" rock (one with many pore spaces), oil can move freely through these spaces. o Source : https://www.priweb.org/ed/pgws/systems /reservoir/reservoir.html Petroleum System SEAL ROCK o Also known as cap rock o A relatively impermeable rock, commonly shale, anhydrite or salt, that forms a barrier or cap above and around reservoir rock such that fluids cannot migrate beyond the reservoir. A seal is a critical component of a complete petroleum system. The permeability of a seal capable of retaining fluids through geologic time is ~ 10-6 to 10-8 darcies. o Source : http://www.glossary.oilfield.slb.com/Terms/s/seal.aspx Petroleum System SEAL ROCK o Source : https://wattsupwiththat.com/2017/0 2/18/oil-where-did-it-come-from/ Petroleum System OVERBURDEN ROCK o Overburden rock is the total stratigraphic section above the source rock. The thickness and age of overburden rock provides a history of the rate of burial of a source rock toward and through the increasing temperature domains of the basin. This includes the range of temperatures necessary for cracking kerogens into hydrocarbons. o Source : http://wiki.aapg.org/East_Breaks_overburden_rock Petroleum System OVERBURDEN ROCK o Source : https://www.slideshare.net/vinayv arghese/introduction-to-ep Exploration Techniques o Magnetic techniques o Gravimetric survey o Seismic method Exploration Techniques MAGNETIC TECHNIQUES o The magnetic method is the study of the distribution of magnetic minerals in the upper 20-30km of the earth's crust. The magnetic method may also be used to estimate the thickness of the crust or to constrain temperatures in the crust using the Curie isotherm (the temperatures at which minerals lose their strong magnetic properties), whichever is shallower. o Magnetic measurements in geophysical exploration record variations in the magnetic field due to lateral variability in the magnetization of the crust. o The lateral variation may produce anomalous regions which are indicative of structural or lithological contrasts in the subsurface. o These data can be collected at the earth's surface, from the air, the sea or in a borehole environment. o Source : http://en.openei.org/wiki/Magnetic_Techniques Exploration Techniques MAGNETIC TECHNIQUES o Magnetic anomalies from 2006 airborne magnetic survey over the Taupo Volcanic Zone, New Zealand. o Source : http://en.openei.org/wiki/Magnetic_ Techniques Exploration Techniques GRAVIMETRIC SURVEY o Gravimetry was one of the first geophysical methods to be used in exploring for oil and gas. As the name suggest, this method uses accurate measurements of the Earth's gravitational field to locate horizontal and vertical variations in the density of subsurface rocks. o The precondition is that the geological structures have to be distinguishable through clear differences in density. o Gravimetric surveys are carried out using extremely sensitive instruments capable of measuring tiny variations in the gravitational field. o Geophysical surveys are performed with gravimeters and are always accompanied by a high-precision topographic survey. o Source : https://www.dea-group.com/en/technology/exploration/gravimetry-magnetics- and-electromagnetics Exploration Techniques Gravimetry applications include: Regional geological mapping; Detection of karsts and voids; The determination or improvement of terrestrial geoid; The oil and gas exploration Mineral exploration; Measurements of sediment thickness; The archaeological surveys. Source : https://www.dea- group.com/en/technology/exploration/gravime try-magnetics-and-electromagnetics Exploration Techniques SEISMIC METHOD o Seismic ground geophysical methods are techniques based on the study of the propagation of seismic waves. The techniques outlined below involve variations in data acquisition and processing, the choice of which will depend on the project goal. Each technique can yield new insights into the subsurface. o Refraction o Reflection o Multi-channel Analysis of Surface Waves (MASW) o Resonance o Borehole Source : http://ground.geophysicsgpr.com/en/ground-geophysics-techniques/seismic-ground-geophysics-methods Exploration Techniques SEISMIC METHOD : Refraction The seismic refraction method involves measuring the shortest time required for an induced seismic pulse to travel from the source location to a series of receivers. From this travel time data, seismic velocities and layer depths can be calculated. Seismic refraction remains the preferred method for accurately mapping the depth to competent bedrock under most conditions. Exploration Techniques SEISMIC METHOD : Reflection The seismic reflection method involves inducing a seismic wave into the earth and recording the waves that are reflected from sub-surface layers. Seismic reflection is ideal for mapping geology at depths exceeding 50 m. Deep seismic reflection surveying is the most advanced technique in geophysics today, thanks to its application on a huge scale for oil and gas exploration. Exploration Techniques SEISMIC METHOD : Multi-channel Analysis of Surface Waves (MASW) The Multi-channel Analysis of Surface Waves (MASW) is a seismic method used to evaluate the shear-wave velocities of subsurface materials through the analysis of the dispersion properties of Rayleigh surface waves ("ground roll"). The data are collected on the surface without the need of borehole. MASW data collection may be extended to 2D or 3D profiling/imaging. The MASW seismic method allows to obtain the shear wave velocity (Vs) distribution in the ground and bedrock. It can be applied as a 1D sounding or as 2D profiles. Exploration Techniques SEISMIC METHOD : Resonance The seismic resonance, or TISAR (Testing & Imaging using Seismic Acoustic Resonance) method is a new technique based on the frequency analysis of seismic records for high resolution seismic investigation. It considers the seismic resonance within the signal. The method was originally developed for geological sub-surface profiling (1 to 15 m deep); however it has been shown to be effective for ranges smaller than 0.1 m for testing of concrete/asphalt structures, as well as for 100 m deep geological investigations. Exploration Techniques SEISMIC METHOD : Borehole Borehole seismic surveys can be carried out in several different ways. The Down-hole technique consists of measuring the arrival of seismic waves emitted from the surface in increments down the borehole. The Cross-hole technique uses a seismic source located in an adjacent borehole. The receiver in both cases is a tri-axial geophone. This enables profiles of seismic velocities from compressional (P) waves as well as shear (S) waves to be obtained. Accurate 2-D maps of seismic velocity variations between boreholes can be produced by processing the data using specialised software. Borehole seismic techniques include down-hole, cross- hole and seismic tomography methodologies. Exploration Techniques SEISMIC TECHNOLOGY VALUE CHAIN Exploration and Appraisal Well EXPLORATION WELL An exploration well is a deep hole that is drilled into the Earth’s surface with the aim of locating a new source of hydrocarbons such as oil and natural gas. Drilling of an exploration well poses a risk to the company, as it is uncertain how much the company will reap from the new source. Every new oil well was an exploration well at some point. Exploration depends on the technology that is used to detect and determine the amount of these deposits using exploration geophysics. Source : https://www.petropedia.com/definition/6014/exploration-well Exploration and Appraisal Well APPRAISAL WELL An appraisal well is a vertical or deviated well that is drilled so as to understand the potential of a hydrocarbon reservoir before commercial production of oil from a well can commence. The drilling of this well is an important part of the exploration and production activities of an organization. In the chronology of asset development program, appraisal drilling is performed before starting the commercial production. During field appraisal programs, appraisal wells are drilled in order to ensure that the discoveries made during exploration field have enough hydrocarbons that can last long and give an economic appreciation to the organization findings. Once the appraisal wells are drilled they provide information such as physical extent of hydrocarbons, likely production rate from the field, flow of fluids and volume of fluids, etc. Source : https://www.petropedia.com/definition/4584/appraisal-well THANK YOU