Lundin Norway and Partners Concedo and Petoro Efficiently Sample Pure Oil in Fractured Basement Rock | SLB
Case Study
Location
Norway, Europe, Offshore
Details

By digitally integrating downhole automation, pumps with a wide dynamic range, and new dual-packer architecture, the Ora intelligent wireline formation testing platform efficiently obtained pure oil samples in low-permeability fractured basement rock in less than 90 minutes on station.

Products Used

Lundin Norway and Partners Efficiently Sample Pure Oil in Fractured Basement Rock

Ora intelligent wireline formation testing platform speeds dual-packer setting and fluid cleanup to acquire clean samples in 90 minutes despite low permeability

Fluid sampling challenges

Extracting oil from basement rock is difficult and can take many hours before an acceptable level of contamination is achieved. Some fractures are present in Lundin Norway’s targeted basement formation but are often of low conductivity. The matrix is mostly of low permeability.

What was tried first

A dual-packer wireline formation testing configuration is typically the toolstring of choice in this environment, but it is historically associated with long station times. Inflating the elements can take as much as 30–40 min. Then fluid contents of the borehole interval isolated between the packer elements has to be cleaned of mud and mud filtrate. Despite the resulting long station time, samples typically still have levels of immiscible contamination that significantly reduce the sample volume.

Sampling in water-based mud from the fractured basement formation from top and bottom inlet, Ora platform.
Sampling in water-based mud from the fractured basement formation from top and bottom inlet, Ora platform.

During sampling in water-based mud from the fractured basement formation, the interval is initially filled with mud. (1) After pretesting, cleanup pumping begins on flowline 2 from bottom of lower of the dual inlets. (2) Filtrate appears from the bottom inlet. (3) Oil breaks though at the bottom inlet. At this point, the top inlet is in 100% oil. (4) When pumping starts on flowline 1 from the top inlet, oil is observed. (5) Pure oil flows on flowline 1 after the commingle valve is closed.

What Schlumberger recommended

The new Ora wireline formation testing platform integrates high-flow-rate pumps and dual-packer architecture with downhole processing power and intertool communication that enable automation of entire workflows. This digital capability enables inflating the packer elements in as little time as 4 minutes, cutting the traditional inflation time by at least 85%. Once the interval is isolated, the  pumps and dual-inlet configuration are highly effective at separating formation oil from immiscible mud filtrate, as validated by downhole fluid analysis.

What Lundin Norway achieved

Lundin Norway’s deployment of the Ora platform with the dual-packer system was the first deployment worldwide of this configuration. The platform acquired pure samples of oil with a high  level of efficiency that company representatives said, ”will definitely change the way we will approach formation testing in the future.”

Automatic inflation of the Ora platform’s dual packer elements in the 8.5-in borehole started at 0.5-min station time at a rate of 55 cm3/s. At 2.7 min, the inflation pressure rose as the elements contacted the borehole wall. The pump rate was automatically ramped down to ease the elements against the formation. When the inflation pressure reached the user input of 400 psi, the pump stopped. While one flowline managed the inflation into the elements, the second flow line continuously equalized the interval pressure. In less than 5 min on station, the dual packer was ready for the first drawdown to be conducted.

Inflation pressure and volume of the Ora platform's dual packer elements. In less than 5 min on station, the dual packer was ready for the first drawdown to be conducted.
Inflation pressure and volume of the Ora platform's dual packer elements. In less than 5 min on station, the dual packer was ready for the first drawdown to be conducted.
Products Used

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