Pressure Transient Data
Acquisition and Analysis Using Real Time Electromagnetic Telemetry, L.E.
Doublet, J.W. Nevans, M.K. Fisher, R.L. Heine, T.A. Blasingame, SPE 35161,
March 1996.
ABSTRACT
Pressure Transient Data
Acquisition and Analysis Using Real Time Electromagnetic Telemetry
This paper presents the
operational procedures and the results for two pressure buildup tests
performed using a wireless telemetry acquisition system (TAS) tool at the
Northern Robertson (Clearfork) Unit (NRU) in Gaines, Co. Tx. Using a single
pressure gauge system downhole, we obtained real-time telemetry of pressure
and temperature data at the surface, as well as a larger sampling of data
that were stored in the downhole memory system.
This new wireless telemetry
acquisition system was developed to provide real-time pressure and
temperature data at the surface by using an electromagnetic signal to
transmit these data through the formation strata. The tool is fully
programmable so that a wide range of sampling frequencies can be used. The
system allows pressure and temperature data to be stored downhole (as in the
case of a typical "memory" gauge), or these data can be
transmitted to surface data acquisition systems. This provides real-time
pressure and temperature data for pressure transient tests, stimulation
monitoring, and long-term reservoir surveillance.
Our objective is to
demonstrate the use of this technology for pressure buildup tests in low
permeability reservoirs. Our goal in utilizing this technology is to reduce
the shut-in time requirements for pressure transient tests, which will
ultimately result in a more cost-effective reservoir surveillance program as
wells can be returned to production (or injection) as quickly as possible.
Once the pressure data were
acquired, we performed conventional semilog and log-log analysis, and we
simulated test profiles to verify the analyses of the test data. Both
surface and downhole pressure data were compared for consistency, and both
types of data were analyzed in exactly the same fashion. The results of
these analyses were essentially identical. This approach gave consistent
estimates of reservoir pressure, permeability, skin factor, and fracture
half-length for both of our case histories.