Summary
Flow rate and fluid type (phase) are two of the most fundamental parameters
needed to characterize well performance. Traditional methods of estimating
these parameters, particularly for real-time detection and diagnosis of
production anomalies, have been limited by sampling frequency and data quality.
This paper presents field-test results of a new type of downhole multiphase
flowmeter, which confirm the value of permanent downhole metering. The meter
contains only three sensors but is capable of direct multiphase-flow-rate and
cut measurements without slip models, even in highly deviated, recirculating
flow. The physics basis and flow loop tests are discussed.
Introduction
Well monitoring, surveillance, and problem diagnosis are critical parts of
the production business, and many production parameters are monitored in the
process. Of these, flow rate and fluid type (phase) are two of the most
fundamental measurements. Over the years, many instruments have been used to
collect and process flow data, including production-logging tools, surface-test
separators, and surface multiphase flowmeters, but none of these provides a
complete information solution.
Production logs provide flow information as a function of depth, but only
intermittently in time. In addition, production-logging tools are complicated,
especially those designed for deviations beyond 45° from vertical, in which
sophisticated hardware with arrays of sensors must be combined with empirical
slip models to cope with nonuniform and unsteady flows. Nevertheless,
production-logging tools are routinely used to update reservoir models and
diagnose problems. In some cases, problems are discovered when using these
tools that would never be diagnosed on the basis of surface measurements (Lenn
et al. 1998).
A traditional method of flow analysis relies on routine periodic production
testing through a separator and back allocation of production over the
intervals between tests. Restricted access to a test separator often imposes
constraints on when this information can be gathered, and the empirical
relationships used to estimate rate between valid tests are often hampered by
errors and uncertainties associated with varying flow conditions and data
limitations.
Finally, surface multiphase flowmeters may have limitations when gas/oil
ratio (GOR) is high because of the high volume of associated gas that evolves
from the liquid stream as it flows up the well, complicating the determination
of oil and water volumes. On platforms servicing many wells, there may not be
enough room to install a meter on each well, thus preventing continuous
flow-rate and cut measurements on each well. This introduces the same type of
uncertainty because of varying flow conditions, as found in the test-separator
method.
© 2006. Society of Petroleum Engineers
View full textPDF
(
1,796 KB
)
View Cart
