Abstract
Integrated Produced Water Management – Experiences and Challenges
Managing produced waters properly, or not doing so, can have immense impacts on oilfield economics, in quite obvious capital and operating expenditures, but also in less obvious but potentially high cost items, such as:
- Financial penalties (fines) for exceeding oil-in-water discharge limits, to sea or other surface water courses;
- Charges from waste disposal companies (including pipeline and terminal operators receiving wet oil or produced water);
- Public relations impacts (including impact on share prices);
- Legacy costs for past, current and perhaps future wastes e.g. oily sludge disposal pits, evaporation ponds and ‘toxic’ waters discharged to rivers, etc.;
- Reduced recovery/production of oil reserves, as a result of shutting in ‘wet’ wells, reduced injectivity in produced water re-injection (PWRI) wells - with potential impacts on reservoir voidage replacement and conformance;
- Production shut-ins if out-of-specification water cannot be disposed of;
- Unnecessary maintenance costs on work-overs, repairs and replacements, e.g. due to avoidable corrosion and scaling.
The objective to ‘integrate’ produced water management is a very obvious one, most particularly for the cycle of water from water injection (WI & PWRI), through the reservoir, production wells, flowlines and processing facilities, and again on to PWRI.
However, the less obvious items noted above typically do need to be integrated into the overall produced water management process. In addition, a wider role for produced water management must be considered, in some cases, for:
- Conversion of produced water to irrigation or potable water;
- Suitability for carriage of EOR agents e.g. chemicals such as alkalies, surfactants and polymers (or combined ASP), bacteria and/or nutrients for microbial EOR (MEOR), or associated with gas injection (WAG, SWAG);
- Associated with CO2 injection for carbon capture and sequestration (CCS).
Some of the above items are discussed in more detail below, with examples.
