Water production normally increases as field gets more matured; especially for fields developed via water injection or natural aquifer support. Handling water production is always a challenge from both financial and environmental prospects. The field under study is a giant oil and gas producer in Gulf area. Before embarking on the PWRI project, the routine way to handle the field's water production (~65 Mbbls/d) was to dispose through dedicated wells drilled only for that purpose and completed as open hole in Dammam, Simsima and UER formations. On the other hand, the water injection project sourced by water supply wells drilled and completed with ESP's through the same formations.
In 2010, PWRI project was commenced through replacing the aquifer water injection by produced water re-injection in one of the water injection clusters without water treatment. Since then, about 22–29 Mbbls/d of produced water are being injected through four water injection wells. After commencing the project, it was very crucial to assure that, no injectivity impairment due to produced water re-injection in addition to wells' integrity.
The water injection performance was closely monitored as WHIP and injection rate and using some techniques like Hall plot to detect any injectivity impact. Pressure fall-off tests (PFO) were frequently performed to detect any formation damage associated with PWRI. Moreover, PLT was performed in one of the wells before and after switching from aquifer water to injection water. The two logs were compared and proved that, there is no change in the injection profile across the horizontal section of that well. Corrosion logs were also utilized showing that, no integrity issues related to PWRI. As of now, some 24 MMbbls of produced water were injected with no impact on wells' injectivity or integrity.