Innovative technologies for paraffin deposit removal in oil tubing to enhance oil recovery: a mechanical approach

Abstract

Asphaltene - resin - paraffin deposits (ARPD) on the inner wall of production tubing shorten service intervals, elevate operating expenditures, and frequently induce downtime at mature fields. This paper presents the design and field performance of a rod-driven in-well scraper that provides continuous tubing cleaning during routine sucker-rod operation without chemical dosing or surface interventions. The scraper sub is inserted into the rod string and is compatible with Ø73 - 89 mm tubing and Ø19 - 22 mm rods. Performance was evaluated on a before/after basis using the inter-cleaning period (ICP), downtime, and annual cleaning costs, with extrapolation to multi-well programs. Field deployments of model CP TP ST 01KZ achieved an ICP of 144 - 280 days with zero cleaning-induced downtime (0 days yr⁻¹). Annual cleaning costs were ~0.265 million KZT per well (scheduled service only), which is ≈31× lower than hot-wash budgets on the same asset. The implied per-well saving is ≈7.94 million KZT yr⁻¹; for a 50-well program, this corresponds to ≥397 million KZT yr⁻¹ in avoided expenditure. Continuous in-well action of the reciprocating toothed head on each rod stroke disrupts the boundary wax layer and limits deposit regrowth between services, eliminating periodic thermal/chemical treatments and their logistics. The subassembly mass (≈30 kg) permits installation with standard handling; the pump string configuration is unchanged apart from the insertion of the scraper section. Compared with thermal, chemical, and batch mechanical methods, the technology extends service intervals, removes cleaning-related shut-ins, and compresses the cleaning budget to a predictable, low annual service cost. The results support routine use of rod-driven scraping for ARPD control in wax-prone wells and provide quantitative guidance for field-scale rollout and further optimization (wear resistance, centralization tolerances, and application in deviated completions).