Page 259 - Introduction to Petroleum Engineering

246 TRANSIENT WELL TESTING
12.5 SUMMARY OF TRANSIENT WELL TESTING

Transient well tests can provide information about individual well performance,
wellbore damage, reservoir pressure, reservoir fluid flow capacity, and forecasts of
fluid production. PTT can be used to estimate reservoir permeability, well skin, the
distance to reservoir boundaries, structural discontinuities, and communication
between wells. Deliverability tests provide a relationship between flow rate and
flowing wellbore pressure and can be used to estimate AOF rate.
Many transient well tests are performed on a single well, while others require
changing rates or monitoring pressures in two or more wells. The wells can have dif-
ferent orientations and can be in many different geologic environments including
both conventional and unconventional reservoirs. The number of transient well tests
is limited by factors such as cost and the desire to continue production without
interruption.
Transient well test validity depends on the quality of measured production data as
well as data used in the calculations, such as fluid property data, rock compress-
ibility, formation thickness, and porosity. One way to improve the interpretation of
transient well tests is to compare transient well test results with geological and geo-
physical models of the reservoir. There should be consistency in the interpretations.

12.6 ACTIVITIES

12.6.1 Further Reading
For more information about transient well testing, see Economides et al. (2013),
Satter et al. (2008), Horne (1995), Earlougher (1977), and Matthews and Russell
(1967).

12.6.2 True/False

12.1 The LIT test is the laminar–inertial–turbulent gas deliverability test.
12.2 The falloff test measures pressure increase after an injection well is shut in.
12.3 The buildup test measures pressure increases after a producing well has
been shut in.
12.4 Pressure communication between wells means that a pressure change at one
well can be detected at another well.
12.5 Pressure buildup and pressure drawdown tests are conducted in production
wells.

12.6 The diagnostic analysis of a transient well test begins by plotting pressure
versus time on a Cartesian plot.
12.7 Horner time has the unit of time.