1. n. [Well Completions

What is water drive?

When reservoir pressure drops due to production, the compressed water in an aquifer expands into a reservoir and it helps pressure maintenance. This mechanism is called “water drive”. … Water from an aquifer below a reservoir pushes oil towards producing wells and eventually producing wells will have higher water.

What is gas cap in oil drilling?

1. n. [Well Completions] The gas that accumulates in the upper portions of a reservoir where the pressure, temperature and fluid characteristics are conducive to free gas. The energy provided by the expansion of the gas cap provides the primary drive mechanism for oil recovery in such circumstances.

What is depletion drive?

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.

What is natural drive mechanism?

The natural energy of a reservoir can be used to move oil and gas toward the wellbore. Used in such a fashion, these sources of energy are called drive mechanisms. … Drive mechanisms are determined by the analysis of historical production data, primarily reservoir pressure data and fluid production ratios.

What is water drive in oil and gas?

1. n. [Well Completions] A reservoir-drive mechanism whereby the oil is driven through the reservoir by an active aquifer. As the reservoir depletes, the water moving in from the aquifer below displaces the oil until the aquifer energy is expended or the well eventually produces too much water to be viable.

What is gravity drainage?

Gravity drainage is a recovery process in which gravity acts as the main driving force and where gas replaces the voidage volume. In other words, it is a gas/oil displacement in which gravity forces are dominating.

What is active water drive?

The term active water drive refers to the water encroachment mechanism in which the rate of water influx equals the reservoir total production rate. Active water-drive reservoirs are typically characterized by a gradual and slow reservoir pressure decline.

What is reservoir drive?

Natural forces in the reservoir that displace hydrocarbons out of the reservoir into the wellbore and up to surface. Reservoir-drive mechanisms include gasdrive (gas cap or solution gasdrive), waterdrive (bottomwater drive or edgewater drive), combination drive, and gravity drainage.

What is recovery factor?

Recovery factor (RF) is the overall proportion of oil expected to be extracted from the UKCS. Over time, RF efficiency has increased; but with field complexity also increasing, the result is that overall RF has changed very little.

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What is an oil leg?

The overlying gas zone is referred to as a primary gas cap. In addition to free gas, gas caps usually contain connate water and residual oil. The underlying oil column is sometimes referred to as an oil leg. … Producing wells usually are completed only in the oil leg to minimize gas production.

Why is Bubblepoint pressure important?

The prediction/determination of reservoir bubble point pressure is important because it will help manage the production from oil reservoirs (Coats and Smart, 1986 and Hosein and Dawe, 2014). P is the average reservoir pressure.

What is free gas initially in place?

Original oil in place (OOIPoriginal oil in place) and original gas in place (OGIPoriginal gas in place) refer to the total volume of hydrocarbon stored in a reservoir prior to production.

What are examples of drive mechanism?

• Water drive.
• Gas expansion.
• Solution gas.
• Rock or compaction drive.
• Gravity drainage.

What is secondary gas cap?

As the reservoir pressure in a solution-gas system falls, liberated gas may migrate to the top of the reservoir, producing a secondary gas cap. If the oil is produced rapidly, gas bubbles may form and expand in the pores of the rocks, which can impede oil flow through the reservoir.

What is saturated oil reservoir?

Saturated oil reservoir: When the initial reservoir pressure is equal to the bubble point pressure of the reservoir fluid, as shown in Fig. … Gas-cap reservoir: When two phases (gas and oil) initially exit in equilibrium in a reservoir; the reservoir is defined as a gas-cap reservoir.

Why is water seal a chest tube?

The middle chamber of a traditional chest drainage system is the water seal. The main purpose of the water seal is to allow air to exit from the pleural space on exhalation and prevent air from entering the pleural cavity or mediastinum on inhalation.

What is drainage and imbibition?

“Drainage” refers to the decreasing saturation of a wetting phase. “Imbibition” refers to the increasing wetting-phase saturation.

Why is there a safety pin on a Penrose drain?

A safety pin or a small tab is usually left at the end of the drain to keep it from slipping into your wound (see Figure 1). How long you have your drain depends on your surgery and how much fluid is draining from your incision. As your incision heals, you’ll have less fluid.

What is pressure buildup test?

1. n. [Well Testing] The measurement and analysis of (usually) bottomhole pressure data acquired after a producing well is shut in. Buildup tests are the preferred means to determine well flow capacity, permeability thickness, skin effect, and other information.

What is steam injection wells?

Steam injection is a very well understood EOR method, used commercially since the 1960s. The injection of steam lets heat the crude oil in the formation thus lowering its viscosity and vaporizing some of the oil to increase its mobility.

What is an aquifer reservoir?

An aquifer stores its water in permeable geologic material (unconsolidated sediments or rock), and we need to drill wells and install pumps to pull water out of the aquifer. A reservoir (by the common water resources definition) is a large open body of water on the Earth’s surface – and is typically dammed.

What is combination drive reservoir?

The mechanism of displacement by fluids can be reproduced artificially by strategically injecting water or gas in wells, and this method can be combined with natural mechanisms as gravitational segregation and/or capillary expulsion, increasing recovery.

Which gases are recovered from crude oil?

Gas injection, which uses gases such as natural gas, nitrogen, or carbon dioxide (CO2) that expand in a reservoir to push additional oil to a production wellbore, or other gases that dissolve in the oil to lower its viscosity and improves its flow rate.

What is secondary recovery in oil and gas?

1. n. [Enhanced Oil Recovery, Enhanced Oil Recovery] The second stage of hydrocarbon production during which an external fluid such as water or gas is injected into the reservoir through injection wells located in rock that has fluid communication with production wells.

How do I find my water drive reservoir?

Third, the change in reservoir pressure also can be a helpful indicator. Strong waterdrive reservoirs are characterized by a slow or negligible pressure decline. Thus, a slower-than-expected pressure decline can help indicate a waterdrive.

What is water coning in a well?

Coning is a production problem in which gas cap gas or bottomwater infiltrates the perforation zone in the near-wellbore area and reduces oil production. … Likewise, water coning should not be confused with water production caused by a rising water/oil contact (WOC) from water influx.

What is water influx?

1. n. [Well Testing] The replacement of produced fluids by formation water. Most petroleum reservoirs are underlain by water, and water influx into a reservoir almost always takes place at some rate when gas or oil is produced.

How do you calculate gas recovery factor?

Boi = formation volume factor = 1.05 + (N × 0.05), where N = number of ft3 of gas produced per bblbarrels of oil (gas-oil ratio or GOR). For example, if a well has a GORgas-oil ratio of 1,000, then Boi = 1.05 + (10 × 0.05) = 1.1.

How do you calculate volume factor?

Formation volume factor is defined as the ratio of gas volume at reservoir condition to the gas volume at standard condition, that is,(2.45)Bg=VVsc=pscpTTscZZSC=0.0283zTpwhere the unit of formation volume factor is ft3/scf.

What is primary gas cap?

A gas cap present at the time of the discovery of the oil reservoir is known as a primary gas cap. Certain oil reservoirs are discovered with an initial reservoir pressure below the bubble point pressure where a primary gas cap forms long before the reservoir is discovered and produced.