Client sites
10 20 30 40 50 60
Weak rock, UCS = 20 MPa with different perforation diameters perforation = 25.4 mm perforation = 12.7 mm perforation = 7.62 mm Diameter of Diameter of Wellsites Diameter of
10 Wellsite
20
30 Pore pressure, MPa
40
50
60
WellWatcher service Interpretation Center
> Real-time monitoring and control. The negative effects of producing sand and the impact of sand-control efforts can be observed by various downhole and surface measurements. In today’ s connected oil eld, massive amounts of data can be transmitted and sent directly to asset teams and Schlumberger experts for interpretation. The data can be used to update and verify sand-prediction models and reservoir simulators, and to facilitate complete and real- time production optimization.
the MDT drawdown pressures were kept within safe limits, as defi ned by the sand-failure analysis. In combination with the dual packer, two
other MDT probes were positioned above the dual-packer module to conduct vertical interfer- ence tests. These tests determined vertical permeability along with the standard horizontal permeability. The MDT operations were com- pleted successfully and safely, with no evidence of sand failure. Armed with the MDT test results and samples, Unocal is now better prepared to exploit the Wilcox reservoirs in the Trident prospect.
Monitoring Sand Production
Determining the critical drawdown for various stages of reservoir depletion at which wellbore or perforation failure begins to occur is a primary function of the 3D sand-prediction tool. An
important element of controlling the extent of sand production is managing the pressure draw- down and production rate throughout the life of a well. Monitoring sand-production rates helps optimize production rates, calibrate models, improve sand-control methods and assess the need for remedial work. This practice is central to proper reservoir management. But how do pro- ducing companies know if their sand-exclusion and sand-prevention efforts are paying off, or whether and when remediation is required? Several methods are used to monitor sand
production, and the success of these depends on the extent of the problem and the nature of the well and the completion. Surface-detection methods use sensors located at strategic posi- tions in flowlines. For example, nonintrusive ultrasonic sensors that detect particles colliding with the interior pipe wall can be installed after bends in subsea gathering lines. Over time, these recordings can be used to determine whether
sand production is increasing or decreasing, and can facilitate the estimation of hardware erosion. Periodic downhole measurements help evalu-
ate the effectiveness of sand-prevention methods over time. For example, production logs or well tests record pressure and fl ow-rate data to evalu- ate damage to the completion. Gravel-pack characterization can be accomplished using one or a combination of wireline measurements, including RST Reservoir Saturation Tool, CHFR Cased Hole Formation Resistivity, TDT Thermal Decay Time and CNL Compensated Neutron Log data. These devices allow completion and production engineers to locate the top of a gravel-pack completion and determine its cover- age and quality.34
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Oilfi eld Review
Wellbore pressure, MPa
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