# What is a falloff test?

## What is a falloff test?

A falloff test is a pressure transient test that consists of shutting in an injection well and measuring the pressure falloff. The falloff period is a replay of the injection preceding it; consequently, it is impacted by the magnitude, length, and rate fluctuations of the injection period.

How do you calculate injectivity index?

For example, if the target injection rate q for a proposed project is 1 million MT yr−1, and its injectivity index J is ∼1000 MT/yr/psi, then the expected pressure buildup will be ΔP = q/J = 1 million /1000 = 1000 psi.

What is injectivity test in oil field?

1. n. [Production Testing] A procedure conducted to establish the rate and pressure at which fluids can be pumped into the treatment target without fracturing the formation.

### What is an injectivity test?

Injectivity Test: A well testing technique conducted upon completion of a well. Water is pumped into the well at a constant rate until a stable pressure is reached then the pump is turned off and the rate at which pressure decreases is measured. An injectivity test is a method for testing a wells permeability.

What does it mean when a well goes on vacuum?

vacuum, space in which there is no matter or in which the pressure is so low that any particles in the space do not affect any processes being carried on there. It is a condition well below normal atmospheric pressure and is measured in units of pressure (the pascal).

What is a step rate test in oilfield?

1. n. [Well Completions] A test performed in preparation for a hydraulic fracturing treatment in which an injection fluid is injected for a defined period in a series of increasing pump rates.

## What is productivity index?

The productivity index is a measure of the well potential or ability to produce and is a commonly measured well property1. The symbol J is commonly used to express the productivity index; as well as, being the preferred symbol by the Society of Petroleum Engineers.

What is a Hall plot?

Hall Plot Method: This is a technique for continuous monitoring that was developed by Howard Hall in 1963. It is an effective way to process water injection information. The main concept is to plot a cumulative pressure time product against the cumulative volume of water that has been injected.

What does Injective mean in math?

one-to-one function
In mathematics, an injective function (also known as injection, or one-to-one function) is a function f that maps distinct elements to distinct elements; that is, f(x1) = f(x2) implies x1 = x2. In other words, every element of the function’s codomain is the image of at most one element of its domain.

### How deep can a vacuum pump work?

Since real-world pumps are incapable of producing a perfect vacuum, a more realistic limit of 7m or 8 m can be calculated. This is the point where the weight of water in the hose equals the force from the difference between atmospheric pressure and the less-than-perfect vacuum the pump is producing.

What is a step rate test?

A Step Rate Test (SRT) is a method used to accurately measure the fracture pressure (or formation parting pressure) of a given geologic formation.

What is formation parting pressure?

The parting pressure can be determined from a plot of pressure at the end of each injection step against the corresponding rate for that step. Ideally, the plot exhibits straight line behavior below parting pressure and a reduced slope when parting pressure is exceeded.

## What is a a falloff test?

A falloff test is a pressure transient test that consists of shutting in an injection well and measuring the pressure falloff. The falloff period is a replay of the injection preceding it; consequently, it is impacted by the magnitude, length, and rate fluctuations of the injection period.

In an injectivity test, the well is shut-in until the pressure is stabilized and then injection is begun at a constant rate while recording the bottomhole pressure.

What type of falloff analysis can be used for injected fluid?

If the injected fluid is the same as the reservoir fluid, conventional production well multi-rate falloff analysis can be used.

What is the difference between pressure buildup and pressure falloff tests?

Therefore, a pressure falloff test is similar to a pressure buildup test, but only if the properties of the injected and reservoir fluids are the same. In some falloff tests, the pressure at the wellhead goes on vacuum.