As we discussed in Lesson 2, an undersaturated oil reservoir is defined as a reservoir in which the initial pressure is greater that the bubble-point pressure of the crude oil. This results in a single, liquid hydrocarbon phase in the reservoir. As we discussed, there will be some water saturation in the reservoir also.
What is undersaturated oil reservoir?
As we discussed in Lesson 2, an undersaturated oil reservoir is defined as a reservoir in which the initial pressure is greater that the bubble-point pressure of the crude oil. This results in a single, liquid hydrocarbon phase in the reservoir. As we discussed, there will be some water saturation in the reservoir also.
What is the bubble point pressure of a saturated oil reservoir?
A saturated oil reservoir has a bubble point pressure of 2100 psi at 175°F. The initial reservoir pressure is 2400 psi. The following data summarizes the rock and fluid properties of the field: Original oil–in–place = 10 MMSTB
How is crude oil produced from an underground reservoir?
The initial production of crude oil from an underground reservoir is achieved by the use of the natural energy of the reservoir ( Alvarado and Manrique, 2010 ). As soon as the reservoir is opened, the natural energy comes into play and, whether through gas pressure or water pressure, forces the fluids to the surface facility (primary production).
When should a saturated oil reservoir be waterflooded?
A saturated oil reservoir is under consideration to be waterflooded immediately after drilling and completion. Core analysis tests indicate that the initial and residual oil saturations are 70% and 35%, respectively.
What is saturated and undersaturated reservoir?
Saturated: Reservoir pressure ≤ bubble point of oil. For an undersaturated reservoir no free gas exists until the reservoir pressure falls below the bubblepoint. In this regime reservoir drive energy is provided only by the bulk expansion of the reservoir rock and liquids (water and oil).
What is gas cap reservoir?
Gas cap reservoirs are a special class of hydrocarbon reservoirs that have segregated gas caps and are examples of reservoirs that are at their saturation pressures. The gas and the oil are in equilibrium at reservoir pressure and temperature. Producing a gas-cap reservoir requires special engineering skills.
What is a volatile oil reservoir?
Print. Undersaturated volatile oil reservoirs are single-phase oil systems that reside in reservoirs with an original temperature relatively close to the critical point (relative compared to low shrinkage oils).
What are the five classifications of petroleum reservoir fluids?
Petroleum reservoirs are usually classified into five fluid categories:Dry gas.Wet gas.Gas condensate.Volatile oil.Black oil.
What is a depletion drive reservoir?
A depletion drive reservoir is characterized by a rapidly increasing gas–oil ratio from all wells, regardless of their structural position. After the reservoir pressure has been reduced below the bubble point pressure, gas evolves from solution throughout the reservoir.
Does the reservoir have an initial gas cap?
Gas cap drive In case an oil reservoir does not have a gas cap initially, but one is formed later by the dissolution of volatile components present in the liquid phase, the gas cap is referred to as secondary.
What is the difference between heavy and volatile oil?
Black oils typically range from 70 to 150 in molecular weight but may range as high as 190 to 210. In contrast, volatile oils are lower in molecular weight than black oils and typically range from 43 to 70. Oils with molecular weights greater than 210 usually are classified as heavy oils.
What are the different types of reservoirs?
There are three main types of reservoirs; valley-dammed reservoirs, bank-side reservoirs, and service reservoirs. Valley-dammed reservoirs are created in valleys between mountains. Usually, there is an existing lake or body of water.
What are the two most common types of reservoir rocks?
Reservoir rocks around the world is dominated by sedimentary rocks because generally it has primary porosity. Igneous and metamorphic rocks can be reservoir if there are in fracturing state (secondary porosity).
What are the three reservoir fluids?
The distribution of reservoir fluids (gas, oil, water) trapped in a reservoir is determined by the laws of physics. Gas has the lowest density of the three mediums and is therefore trapped at the top of the reservoir when it occurs in free-phase.
How do you classify reservoir fluid?
However, reservoir fluids can be classified according to the position of the initial reservoir pressure and temperature relative to the phase envelope. To aid in the classification, one more term is defined, the cricondentherm.
What three fluids make up crude oil?
Crude oil is composed of hydrocarbons, which are mainly hydrogen (about 13% by weight) and carbon (about 85%). Other elements such as nitrogen (about 0.5%), sulfur (0.5%), oxygen (1%), and metals such as iron, nickel, and copper (less than 0.1%) can also be mixed in with the hydrocarbons in small amounts.
What means gas cap?
a cover for the end of the pipe through which fuel is put into a vehicle. Determine where the gas cap is located before driving away.
What is the thing called where you put gas in your car?
Fuel filler neck or pipe, it connects to a rubber hose (8) that connects to the tank (1).
What is the gas cap cover called?
What is the name of the gas lid cover? The fuel valve is a metal cover that helps keep debris away from the fuel or fuel tank.
How much does it cost to replace a filler neck?
The fuel filler neck replacement cost differs based on whether you'd like a factory or aftermarket product and your mechanic's labor rate. Generally, you can expect to spend about $200 for the average vehicle.
What is the pressure of a saturated oil reservoir?
A saturated oil reservoir has a bubble point pressure of 2100 psi at 175°F. The initial reservoir pressure is 2400 psi. The following data summarizes the rock and fluid properties of the field:
What is the average reservoir pressure for a well?
A well is producing from a saturated reservoir with an average reservoir pressure of 2,500 psig. Stabilized production test data indicated that the stabilized rate and wellbore pressure are 350 STB/day and 2,000 psig, respectively. Calculate:
What is underground reservoir?
Underground Reservoirs. Underground reservoirs are geological structures that have unique features. There is a porous medium having some degree of permeability. The porosity allows natural gas to be contained within the medium. The permeability allows the gas to move from point to point within the medium. There is almost always an impermeable layer ...
What is the difference between a subsurface dam and an underground dam?
While subsurface dams are relatively shallow structures for collecting water in the alluvial deposits downstream of the spring, underground dams are located at the spring and create water storage inside the primary aquifer.
What is the name of the type of reservoir that is sealed on all sides by impermeable rock?
Underground reservoirs may be classified into two general types: volumetric reservoirs and water drive reservoirs. The volumetric type is sealed on all sides by impermeable rock and behaves like a pressure vessel.
How does water force back into the bucket?
As more gas is introduced into the bucket, water is forced out and the size of the gas bubble inside the bucket increases. The forcing back of the water may occur by two mechanisms. In one mechanism, the gas and a very large amount of water are contained in a large sealed reservoir of constant volume.
Why is a large volume of water required to enlarge a gas bubble?
Because the compressibility of water is quite small, a very large volume of water is required in order to achieve an enlargement in the gas bubble. The second mechanism is where the gas simply pushes the water out of the storage reservoir to some other reservoir or some other location.
What are the two types of gas in underground storage?
Underground storage reservoirs contain two types of gas: cushion gas and working gas. These two types are functional rather than physical. The cushion gas may be native gas that has never been produced, or it may be injected gas that has been produced at some other location and injected into the reservoir.
Where are oil reservoirs found?
Heavy oil reservoir and tar sand deposits are found in the microscopic pores of sedimentary rocks such as sandstone and limestone . Not all of the pores in a reservoir rock or deposit will contain heavy oil or bitumen—some will be filled with water or brine—the latter is water that is saturated with minerals.
What is reservoir drive?
The reservoir drive mechanism supplies the energy that moves the hydrocarbon located in a reservoir container toward the wellbore as fluid is removed near the wellbore. There are five common drive mechanisms: One type usually dominates, but drive types can occur in combination.
Why does reservoir fluid pressure increase?
As reservoir fluid pressure declines, the pressure on the solids, or net confining pressure (P nc ), increases because pore fluid pressure carries less of the weight of the overburden. Some reservoirs respond to the increase in P nc by the collapse of the pore space. This can be an efficient way to expel hydrocarbons.
How does an aquifer work?
The aquifer water expands slightly, displacing the oil or gas from the reservoir toward the borehole as pressure drops around the borehole. This mechanism exists only where the aquifer is of equal or better quality than the reservoir and has a much larger volume than the reservoir (about 10 times) or is in communication with surface recharge. ...
What is partial water drive?
A partial water drive results where an aquifer has poorer quality in terms of pore geometry or has limited volume. When the water support diminishes, the hydrocarbon production rate drops more rapidly than in a reservoir with a strong water drive and recovery is reduced.
Can a gas expansion drive be accompanied by a partial water drive?
Drive mechanisms can occur in combination. For instance, a gas expansion drive is commonly accompanied by a partial water drive. Water drives can be enhanced by imbibition effects, a minor drive type.
What is a dry gas reservoir?
2.13: Dry Gas Reservoirs. Dry gas reservoirs are gaseous hydrocarbon systems that reside in reservoirs with the original temperatures above the cricondentherm. In addition, the surface conditions are also greater than the cricondentherm.
Is the pressure in the reservoir reduced due to production?
Under these conditions, as the pressure in the reservoir is reduced due to production, both the fluids in the reservoir and the fluids in the production system remain a single gaseous phase.
