Hydrocarbon production is associated with the generation of waste and by-products. The safe disposal of produced water, a common by-product, is of prime concern in oilfield operations. Long thought of as an economical and environmental liability, Produced Water Re-Injection (PWRI) provides an unrivaled option that is beneficial on both fronts. The paper identifies the operation's associated opportunities and risks. Emphasis is placed on procedures and best practices compiled during a 10-year, joint industry project (JIP). The overall theme of the paper is injector performance.

PWRI is used in water flooding for the purpose of pressure maintenance and the possibility of Improved Oil Recovery (IOR). The design process must meet production requirements, assure conformance and sweep and achieve desired pressure maintenance. Additional considerations include meeting waste management requirements for disposal volumes and reducing waste. These constraints translate into injector performance metrics and sustained delivery of the injection rate/injectivity. The paper examines the options available for balancing CAPEX (treatment facility, pumping equipment, and well drilling and construction) and OPEX (filtration, chemical, and biological treatment, stimulation and voidage replacement) to ensure long term injectivity maintenance.

Addressed are selection criteria for well completion, injection and thermal treatment. Issues such as vertical vs. horizontal wells, matrix vs. fractured or cool vs. hot water injection are tackled. Investigated are the damage mechanism and their effect on extended injection. Identification of the damage cause is paramount in guiding the design of an effective stimulation treatment or intervention. The optimal injection design provides the equilibrium between how to mitigate (selection of appropriate water quality) and when to remediate (plan effective stimulation) damage. Several field examples are included to support the conclusion and recommended best practices discussed in the paper.

Monitoring is an essential task during injection. The primary product of which is large amounts of raw data. The paper investigates the use of non-deterministic models and data mining techniques in ascertaining the physical correlations and observations from the data. A field case from the North Sea illustrates this application.

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