Two properties are required for fluid movement of Reservoir rocks and Source rocks: permeability and porosity. It consist voids or pores, ability to contain fluid (known as porosity) and the pores are interconnected (permeability) in order to allow flow to occur. Hydrocarbons can be termed as reservoir fluid. The volume of hydrocarbons stored in a reservoir depends upon the porosity of the reservoir rock. The rate and volume at which hydrocarbons are withdrawn depends upon the permeability of the reservoir rock. Almost complete pore space of the superior several kilometres of earth’s crust contains water. Therefore in this water environment hydrocarbons exist with amalgamation of oil, gas and water occurring in different proportions.
The two dominant physical properties of oil and gas that enhance their movement through subsurface substance are their relative immiscibility in water and their lower density than water which causes their buoyancy. Buoyancy of the hydrocarbons occurs because of differences in densities of respective fluids while transcend via the oil and gas reservoir is a stimuli which creates differential pressures that exist in a reservoir bed.
The basic properties of rocks can be classified as the following:
Skeletal
The "skeleton" structures of the rocks of reservoir are affected by the depositional surrounding and numerous earth processes after deposition.
Dynamic
This is related to the blending of the fluids and rocks of the reservoir. Skeletal properties of interest to reservoir engineers include porosity, pore size distribution, compressibility, and absolute permeability of the rod. Interaction or dynamic properties of reservoir rocks are affected by the nature and by its interaction with present fluids, as...
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...a producing well is significantly lower than at other areas where no well is drilled. The driving force could be either natural or created by engineering design involving fluid injection through certain wells placed optimally to achieve the best results. Experimental data suggests that reservoir rocks are abundantly permeable in both vertical and horizontal directions. Among a myriad of factors related to geological and geochemical processes, the permeability of a rock is influenced by the slit, shape, configuration, and connectivity or a porous network.
Darcy Equation and its Application
Darcy’s law provides an accurate description of the flow of ground water in almost all hydrogeological environments. Henri Darcy established empirically that the flux of water through a permeable formation is proportional to the distance between top and bottom of the soil column.
All naturally occurring stone arches are formed by the selective erosion of rock, but the terms by which this can occur are massive. Among the most frequent types of formation are wave action and lava flow. During wave action, water crashes constantly upon the rock, effectively accelerating erosion while sediment carried by the water is extremely abrasive, removing bits of rock. When lava flow occurs, the outermost la...
From this drive, information such as pressure, GOR and fluid production history can be known. The pressure can drop greatly if the reservoir is initially under saturated due to the fact that compressibilities of rock water and oil is lower compared to gas. F...
Fracking is a procedure that uses high-pressure fluids to obtain shale gas through the drilling of underground rocks. According to Broderick et all (2011), shale gas1 is found trapped within the shale2 formations, it is a very flexible substance as it has a wide range of uses, such as automobile fuels, domestic use and power generation. Nowadays, the gas demand is increasing vastly. Shale gas is one of the main sources of energy for some countries, such as United States of America and United Kingdom (Broderick et al. 2011). The low permeability3 of the shale makes difficult the flow of the gas inside it, therefore, it makes inviable to extract the substance without the support of hydraulic fracturing. Higher the permeability of a rock, higher the flowing of the fluid on it (King 2012). In order to improve the shale gas extraction, a high pressure mixture of water, sand and other additives is injected in the rock to increase its fractures and facilitates the flowing of the gas and its capture (Howarth et al. 2011). The figure below illustrates the fracking process.
Rock thickness will have enough permeability to transcend fluids towards a bore well. This characteristic is usually called as “Net reservoir rock.” In the oil and gas industry, another quantity “Net Pay” is computed which is the rock thickness which can transcend hydrocarbons to the bore well at an optimum rate. Reservoir models are built upon their measured and derived properties to estimate the amount of hydrocarbon present in the reservoir, the rate at which that hydrocarbon can be produced to the Earth’s surface through wellbores and the fluid flow in rocks. As far as Industry of Water Resources is concerned, likewise models are utilized to analyse amount of water that can be produced to the surface over long periods of time, without depleting the aquifer.
This exercise gave me an opportunity to put into practice geologic concepts, such as sorting, rock texture and environmental indicators like joints in determining the geologic history of a rock. With the help of our professor, my classmates and I were able to determine that the rock, which was a congramerate sedimentary rock composed of sandstones gravels and milky quartz minerals. The outcrop was composed of beddings consisting of layering of fine followed by coarse particles. This observation indicated that the rock might have resulted from deposition of sediments by a river with seasonal variation in the volume of water, particularly, a braided river. Also, by observing the orientation of some of the rock particles on the outcrop and sorting of the rock sediments, we were able to determine the evidences for flooding and variation in the force that transported the particles as they were deposited to for the
The role of shale oil, shale gas, tight oil and tight gas reservoirs, generally classified as unconventional reservoirs, in meeting with the ever-increasing energy demand has come under serious considerations in recent times. While significant successes have been achieved in getting some of these resources out of the ground, detailed understanding on the mechanisms that interplay in these types of reservoirs for their optimal productivity has not being thoroughly researched. This often result in significant hydrocarbons still left unrecovered after such reservoirs have been put to production using existing models and methods of recovery. In essence, there seems to be a need for better characterization of these unconventional reservoirs if they must be developed and produced optimally. It is on this premise I intend pursuing a PhD program with the hope of advancing knowledge that could help solve some part of the problem.
There is also a form of breccia that is found on the floor of craters. Like most breccia’s, these are made up of fine grained sediment with other fragments of rock set inside; however, the rock fragments are mixed violently and chaotically rather than the more orderly formation found outside of the crater’s rim. This particular type of breccia was first noticed by Danie...
Hydrocarbon recovery forms the crux of the oil and gas energy. Ever since petroleum was established as a source of energy, the oil and industry has always persevered to improve and optimize conventional recovery techniques in an effort to boost production and profits. Nevertheless, the increased over- dependency on hydrocarbons has exhausted reserved from the most commercially viable wells/plays, which is to say that wells requiring standard exploration and production techniques are now on a decline. However, oil and gas deposits are very much available in many regions as shown in Figure 1.1. Most of them exist as unconventional resources usually treated as possible reserves.
Every rock group has a different depositional environment. For example, the Kawr group represents the Oman Exotics and is composed of distal sediments (chert). Closer t...
As internal processes, mountain building and volcanic activity, elevate Earth’s surfaces, external processes, weathering and erosion, breakdown and move Earth’s surfaces down slope. It’s a continuous rock cycle, and water movement contributes greatly to Earth’s external weathering and erosion processes, sculpting earth’s surfaces throughout the course. As water evaporates from the ocean and precipitates over the mountains, river systems are established; and in their many shapes and forms, move eroded rock material from the surface towards the ocean, further disintegrating material along the way. River systems move Earth’s surface materials, while shaping its landscapes.
Permeability is a measure of the ease of flow of a fluid through a porous solid. A rock may be extremely porous, but if the pores are not connected, it will have no permeability. Likewise, a rock may have a few continuous cracks which allow ease of fluid flow, but when porosity is calculated, the rock doesn't seem very porous.
Hydrocarbons are compounds formed by carbon and hydrogen atoms. They are used as fuels to produce energy in incomplete and complete combustion reactions. Incomplete combustion occurs when hydrocarbons react with a small amount of oxygen (O2), whilst complete combustion occurs when hydrocarbons react with large amounts of oxygen. Incomplete combustions produce water (H2O), carbon monoxide (CO) and/or soot (C). The CO and soot produced from incomplete combustion can have harmful consequences on humans and the environment. They not only damage human health, but also contribute to the current issue of global warming, ozone formation, and black carbon footprint. That being said, CO is vital to the human body in order to properly function.
Permeability is defined as the ability of porous medium to transmit fluids through it. Permeability controls how fluid can migrate through the reservoir. The permeability is a main parameter in reservoir development and management because it controls the production rate. Generally, the permeability increases with increasing porosity, increasing grain size and improved sorting (SeIley, 1998; Tagavi, 2005). In carbonates rocks connectivity between pores is the main control for the permeability. Heterogeneity arises in carbonate reservoirs as a result of variation in depositional environment and subsequence diagenetic processes.
Production changes, carried out during a transient well test, induce pressure disturbances in the wellbore and surrounding rock. This disturbances extend into the formation and are affected in various ways by the rock features. For example, a low permeable rock will restrict the pass of the pressure wave. Therefore, a record of the pressure response over time produces a curve whose shape is defined by the reservoir’s unique characteristics.