Sandvik Materials Technology has launched the first hyper-duplex wireline for use in wells with extreme chloride environments. The new material, Sandvik SAF 2707 HD, was trialed over an eight-month period in wells offshore Indonesia.
The need to push back the barriers of wireline performance was driven by the ever more extreme downhole conditions being encountered in oil and gas wells, says Phil Etheridge, marketing manager for energy products.
SAF 2707 HD, a high-alloy duplex stainless steel, is a stronger alloy with improved corrosion resistance and performance in chloride-intense environments compared with Sanicro 26Mo, and on a par with Sanicro 36Mo, the company’s sour service wireline materials.
The new material has very high mechanical strength and resistance to pitting and crevice corrosion. Its PRE (pitting resistance equivalent) value is a minimum 48, which falls between the two Sanicro grades. It has a service temperature range of - 50º C to 280º C (-58º F to +536º F), which encompasses higher temperature gas wells.
The superior properties of the new steel make it a cost-effective alternative to super austenitic steels and nickel-based alloys in chloride-containing environments.
SAF 2707 HD also meets the potential needs of geothermal wells, where much higher temperatures can be found. In deep geothermal drilling in Iceland, for example, temperatures of 500º C (932º F) and more can be encountered. The new material has been laboratory tested in temperatures up to 600º C (1,112º F) and performed well.
The downhole environment in which tests were held off Indonesia included a chloride content of up to 15,000 ppm, temperatures of 150º C (302º F) and pressure of 5,000 psi (34.5 MPa). Here the durability of the carbon steel wirelines originally used by the customer suffered badly, their operational time being reduced to less than 75 hr.
Various other wirelines were tried. Super-duplex materials produced by competitors achieved 400 hr and Sandvik’s SAF 2205SH 710 hr. However, SAF 2707HD clocked up 1,051 hr before two full days of heavy jarring caused the line to break. The customer was sufficiently impressed to specify this grade for its future requirements.
But the trade-off between cost and performance may make it worth considering the hyper-duplex grade in cases where a conventional carbon steel wireline would normally be used, Etheridge says. With a similar strength to ultra-high tensile strength carbon steel, the hyper-duplex wireline can perform the same work but lasts 10-15 times longer, though its cost is not proportionately as high.
For more information, contact Phil Etheridge, Sandvik Materials Technology. Tel +46 2626 3120, fax +46 2627 4720, [email protected],www.smt.sandvik.com
