Environmental assessment of river water quality near oil and gas fields

BACKGROUND an‎d OBJECTIVES: The research aimed to evaluate the water quality of the Cangkring River in Tuban Regency, East Java Province, Indonesia, at the segment near the oil and gas fields (Mudi Pad A, B, and C). METHODS: Water samples were collected from January to September 2021 at seven locations along the river segment and tested ex-situ using six parameters, including physical, chemical, and microbiological. The pollution index formula was used to calculate, determine, and analyze the river water quality status. Samples at three locations were further tested with 13 additional chemical parameters due to potential contamination by other substances as they were located the closest to the production site and office area. FINDINGS: Sample analysis with six parameters showed a pollution index value of 0.558 or within the predefined standard at one location (SW6) and 1.080–2.721 at the other six locations, indicating slight pollution. Another test at three selected locations (i.e., SW1, SW2, and SW7) with 13 additional parameters increased the pollution index to 5.556–6.170 (moderate pollution). This status change was due to the high presence of nitrite and ammonia in the water samples. CONCLUSION: The oil and gas industry near the Cangkring River has strictly complied with the regulations in treating their produced water. However, it still contains a high amount of nitrite and ammonia, moderately polluting the river water. Therefore, it is necessary to regularly test the river water near oil and gas fields to ensure its quality and safety.