The wireline formation tester (WFT), which engineers use to take pressure measurements, analyze insitu fluids and capture reservoir fluid samples at the formation face, is one of the most powerful tools available for gauging reservoir deliverability and fully characterizing reservoir fluid types and properties.
The data provided by these diagnostic tools provide drilling, reservoir, completion, and production engineers with much of the information they need to optimize well and field designs and production strategies.
However, in certain formations and reservoir fluid types, operators have found it challenging or impossible to capture samples using traditional WFTs. In ultralow-permeability formations or when very high-viscosity fluids are present, or the combination of the two, drawdown pressures required to coax samples through the formation and into the sample chambers of the WFT may be beyond the tool’s pressure rating.
To address this, Schlumberger has introduced the Saturn 3D radial probe. The Saturn probe employs four large intake ports spaced equally around the circumference of the tool to capture samples and measure pressures even in formations with ultralow permeability and high-viscosity fluids.
The ability of the large ports to capture samples with relatively low drawdown pressures also significantly shortens the time required to reduce mud-contaminated fluids—cleanup time—from the near wellbore and allow purer, more representative reservoir fluids to flow to the tool.
An article in the Spring issue of Oilfield Review, “New Dimensions in Wireline Formation Testing,” describes the obstacles operators have encountered using traditional WFTs and the innovations introduced to these tools to overcome such challenges.
Case studies from the Middle East, Mexico, and Norway demonstrate how the latest of those innovations has made capturing samples and pressure measurements possible in even the most difficult formations and fluid types as well as deep water environments.
Read the full article at the Oilfield Review Web site.
Ayan C, Corre P-Y, Firinu M, García G, Kristensen MR, O’Keefe M, Pfeiffer T, Tevis C, Zappalorto L and Zeybek M: “New Dimensions in Wireline Formation Testing,” Oilfield Review 25, no. 1 (Spring 2013): 32–41.
The Saturn 3D radial probe, which uses four ports, increases the probe surface area to more than 500 times that of the standard probe.