Empirical Study of Well Productivity Impairment from Organic Scale Deposition in Gas Condensate Wells of OML 101, Offshore Delta State, South South Nigeria

Organic scale deposition, encompassing paraffin wax, asphaltene, and mixed organic-inorganic composite deposits, can critically impair the productivity of gas condensate wells by reducing tubing bore area and plugging completion intervals, yet the specific deposition mechanisms and remediation effectiveness in offshore Delta State condensate wells have not been empirically documented. This study empirically investigates the mechanisms, severity, and remediation effectiveness of organic scale deposits impairing well productivity in OML 101 gas condensate wells, offshore Delta State. Solid deposit samples recovered during wireline intervention and coiled tubing cleanout operations from seven impaired wells were characterised by solubility testing, Fourier-transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. Results classify the dominant deposit type as high-molecular-weight paraffin wax (C20 through C40 fraction) in four wells and mixed asphaltene-paraffin composite in three wells, with crystallisation onset temperatures between 42 and 67 degrees Celsius measured by cross-polarised microscopy. Production log surveys confirmed that the primary impedance zone is concentrated in the upper 200 metres of completion in all impaired wells, consistent with cooldown wax crystallisation above the critical temperature. Chemical solvent treatments using aromatic solvent blends showed a mean productivity restoration of 68 percent in wax-dominated wells, while asphaltene-dominated wells required xylene injection at elevated temperature to achieve comparable results. Preventive pigging frequency recommendations are derived from wax deposition rate models. Keywords: organic scale, wax deposition, asphaltene, gas condensate wells, OML 101.