Reservoir Test String Delivers Comprehensive Postfracture Evaluation in Highly Deviated, Ultradeepwater Well | SLB

Reservoir Test String Delivers Comprehensive Postfracture Evaluation in Highly Deviated, Ultradeepwater Well

Published: 07/15/2015

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Efficient reservoir assessment needed in ultradeepwater well

An operator needed to assess the commercial viability of a 2,128-m ultradeepwater well in the Santos basin, offshore Brazil. The operator planned a massive multizone fracturing operation followed by a well test to assess the effectiveness of the treatment. Adding to the operation’s complexity, the zone to be tested was in open hole at 6,672-m TD and highly deviated at 72° at the packer depth.

Advanced test system deployed as solution

A permanent packer was already in place and the test string design was planned to be run with the packer seal assembly following the multifracture operation. After consulting with Schlumberger, the operator chose to use IRDV valves in the string, CQG crystal quartz gauges, and SCAR sampling. Because well control was essential for this ultradeepwater test, the operator ran two IRDV valves in the string. The upper IRDV valve was placed in a 49° deviated zone and, together with the DataLatch system, provided reliable downhole data in real time. The lower IRDV valve was run closer to the seal assembly in a 72° deviated zone to serve as a circulating point for cushion displacement and to control the well at the end of the test.

After the test string was in place, the lower IRDV valve was operated to spot the cushion and was then put in sleep mode. Operations switched to the upper IRDV valve to proceed with cleanup and the well test phase with buildup periods monitored via surface readout. At the end of the test, once the data was validated and downhole samples were obtained using SCAR sampling, the upper IRDV valve was put in sleep mode while the lower IRDV valve was reactivated to proceed with well-killing operations.

Test objectives achieved with versatile downhole test string

The combination of two IRDV valves reliably operated for 770 h to allow the DataLatch system to deliver quality downhole data while maintaining control of the well throughout operations. Additionally, the operator acquired uncontaminated, reservoir-representative downhole samples for analysis. The test objectives were met with zero NPT.

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Using the advanced test string in an ultradeepwater well, made it possible to acquire uncontaminated reservoir- representative downhole samples with zero NPT.
Santos Basin, Brazil, South America, Offshore

Challenge: Obtain reservoir testing data and samples with a downhole test string design that can accommodate surface readout operations in a highly deviated ultradeepwater well without compromising well control.

Solution: Deploy two IRDV intelligent remote dual valves in the test string. The upper IRDV value was configured with the DataLatch electrical wireline downhole recorder and transmitter system, and the lower IRDV valve was located closer to the packer seal assembly for well control purposes. Use SCAR inline independent reservoir fluid sampling to provide representative reservoir samples for PVT analysis.

Result: Acquired real-time, reservoir-representative downhole samples for analysis. Met all test objectives operating downhole for 770 h with zero NPT.

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