Petrogas Rima LLC operates more than 280 wells in the Rima Field of southern Oman, using sucker rod pumps to produce heavy oil with an average specific gravity of 21 API. The wells have high angles of inclination or complex trajectories and are characterized by high concentrations of H2S, CO2, and O2. Because of the challenging environment, broken or parted sucker rods were common, amounting to over half the total field failures recorded. The resulting shutdowns were raising costs because of deferred production, workovers, and rodstring replacements.
SLB proposed using its proprietary, field-proven tungsten-alloy-coated sucker rods. Couplings and rods feature high-bonded amorphous tungsten alloy plating over high-strength base metal to enhance resistance to delamination, wear, and corrosion stress cracking. Hardness after heat treating is ≥850 on the Vickers hardness scale. The coating improves corrosion resistance without sacrificing yield or tensile strength.
The new rods were installed in seven wells and have exhibited a dramatically increased run life despite highly corrosive downhole fluids. By significantly reducing workovers, they have enabled Petrogas to lower opex and improve field economics.
| Well | Previous (Conventional) Rod Run Life, d | New Rod Run Life, d | Increase |
|---|---|---|---|
| 1 | 83 | 443 and still running | ×5.3 |
| 2 | 263 | 395 and still running | ×1.5 |
| 3 | 130 | 387 and still running | ×3 |
| 4 | 54 | 376 and still running | ×7 |
| 5 | 192 | 332 (stopped because of unrelated issues) | ×1.7 |
| 6 | 308 | 345 and still running | ×1.1 |
| 7 | 163 | 338 and still running | ×2.1 |
