Dual-String P&A Barrier Evaluation | SLB

Dual-String P&A Barrier Evaluation

Evaluate the A- and B-annulus without inner-pipe removal during well decommissioning

Dual-string P&A barrier evaluation
Dual-string P&A barrier evaluation
How to Reduce Your P&A Time and Costs
Traditional barrier evaluation during plug and abandonment may take several days per well. But watch how you can save up to 20% time and cost on your project.

Well integrity evaluation without removing inner pipe (casing or tubing), saving time and cost

Continuous measurement of well liquid properties in A-annulus and pipe-to-pipe standoff

Industry's only simultaneous A- and B-annuli evaluation with environmental corrections: corrected bond index, segmented bond log, and 360° azimuthal maps

Simultaneously evaluate the A- and B-annulus to reduce plug and abandonment (P&A) costs

During the P&A well decommissioning phase, conventional barrier evaluation operations require removal of inner pipe (casing or tubing) to evaluate the B-annulus and assess well integrity. This traditional approach to barrier or cement evaluation may take several days per well, depending on the operational complexity—increasing rig time and costs. With dual-string P&A barrier evaluation, you no longer have to remove the inner pipe, enabling you to evaluate both the A- and B-annulus in a single run. This approach completely revolutionizes conventional operations to reduce P&A rig days, costs, and overall carbon footprint. And when performing rigless well integrity evaluation logging, you can use the evaluation insights in the P&A job design stage to optimize future opex and minimize contingencies.

Dual-string P&A barrier evaluation
Dual-string cement evaluation vs. single-string cement evaluation
Logs derived from the same well, with (right) and without (left) the inner pipe removed, showing high data quality using dual-string P&A barrier evaluation.

Obtain reliable B-annulus data using deep-array multimode sonic and multimodality ultrasonic measurements

Building on years of innovative well integrity evaluation technology, dual-string P&A barrier evaluation offers the most advanced and accurate method for imaging the annular profile in the B-annulus, overcoming crucial well conditions that may affect B-annulus interpretation.

Dual-string P&A barrier evaluation leverages a unique combination of wireline-conveyed, deep-array multimode sonic (0.5–20 kHz) and multimodality ultrasonic (100–500 kHz) measurements. The low-frequency sonic measurement provides the B-annulus evaluation. Unlike conventional tools that provide only monopole sonic measurement, multimodality ultrasonic measurement from dual-string P&A barrier evaluation provides crucial information such as pipe-to-pipe standoff and A-annulus liquid type. The combination of multimode sonic and multimodality ultrasonic measurements provides a more reliable B-annulus evaluation with radial coverage and azimuthal mapping that applies environmental corrections.

Unique B-annulus deliverables for advanced well integrity evaluation

With the richness of deep-array multimode sonic and multimodality ultrasonic measurements, dual-string P&A barrier evaluation delivers output levels that suit your well objectives and operational requirements. The B-annulus bond index view (Level 1) enables you to evaluate the top of cement or solids and the intervals of poor or moderate bonded sections. To better determine barrier quality, Level 2 uses ultrasonic measurement to apply environmental corrections (minimum recommended level). The segmented bond log derived independently from the eight azimuthal receivers and monopole transmitter provides the bond quality around the casing (Level 3). The most advanced deliverable (Level 4) provides 360° high-resolution images to evaluate the B-annulus.

Deliverables for dual-string P&A barrier evaluation
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Dual-string P&A barrier evaluation deliverables from both deep-array multimode sonic and multimodality ultrasonic measurements, corrected for wellbore environment effects of pipe-to-pipe standoff and varying liquid density in the A-annulus.
OTC Tech Paper—Acoustic Evaluation of Annulus B Barriers Through Tubing for Plug and Abandonment Job Planning
The need to evaluate cement behind multiple casing strings has become critical for well P&A or slot recovery. This technical paper discusses how P&A operations can be optimized in offshore applications using dual-string P&A barrier evaluation technology to reduce the costs associated with rig time and potentially the unnecessary removal of casing strings.
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