Summary
Key factors in framing a produced water management (PWM) strategy include a
company’s internal and external environments, technology, and business drivers.
Emerging trends for establishing an environment-friendly PWM position comprise
adoption of these policies:
- Move toward zero emissions.
- No discharge to surface or seas.
- Waste-to-value conversion.
- Incremental and progressive separation.
- Proactive efforts to influence partners, regulators, and environmental
laws.
This paper covers technical approaches for addressing the production,
separation, and disposal/injection segments of water injection and reservoir
waterflooding procedures and the basis for selecting strategy components and
PWM actions. Best practices result both from comprehensive assessments of
current PWM tools and from the insights obtained from a decade-long joint
industry project (JIP) on produced water re-injection (PWRI).
PWRI for waterflooding or disposal is an important strategy for deriving
value from waste while preserving environmental integrity during exploration
and production (E&P) operations. Advances in best practices and lessons
learned for injector design, operation, monitoring, assessment, and
intervention provide the basis for cost minimization and green operations.
Facility and subsurface engineering are linked through PWM quality targets,
pumping needs, injector completions, and facility constraints. Field cases and
data mining results (Abou-Sayed et al.2005) show the variation in injector
responses and underline the key elements contributing to performance. Field
evidence indicates that injectivities suffer in matrix injection schemes
despite the injection of clean water. Alternatively, injectivity maintenance
using untreated produced water is feasible.
The majority of injectors fracture during injection, thereby impacting
facilities’ statement of requirement (SOR), injector completion, sweep, and
vertical conformance. This paper assesses fracture propagation during seawater
and produced water injection and its impact on injector performance. Models
depicting plugging of formations and fractures, vertical water partitioning,
and well testing are discussed. Best practices are highlighted and the impacts
on injection strategy outlined. Several field cases, as well as water injection
design and analysis tools for quantifying the impact on flood and well
performance, are presented.
Introduction
PWRI technology application for oilfield management has been steadily
increasing over the last decade in various parts of the world (Sirilumpen and
Meyer 2002; Van den Hoek et al.2002; Furtado et al. 2005; Hjelmas et al. 1996).
Successful injection operations have been reported by operators in the North
Slope of Alaska, the west coast of Africa, and the North Sea. PWRI offers the
dual benefit of disposal of oil-filled waste water and solids in an
environmentally safe way and enhanced hydrocarbon recovery by improving
reservoir fluid sweep and pressure maintenance. The successful application of
this technology in the oil field does not depend only on the disposal of
solids/contaminants, but also on the maintenance of injectivity for effective
sweep and injection conformance for improved recovery.
This paper discusses the physical phenomena, namely matrix and fractured
injection, involved in PWRI and the associated issues with regard to
injectivity and facility requirements. A fracture plugging and propagation
model is presented to explain the cyclic injection pressure behavior observed
in some injectors. Thermal fracturing can allow fracture containment and reduce
injection system requirements. Field cases clearly showing the effect of
injection water temperature on fracture pressure and injectivity are discussed.
The knowledge gained from the JIP is used to establish guidelines and best
practices for implementing a PWM strategy.
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
15 September 2005
- Meeting paper published:
21 November 2005
- Revised manuscript received:
13 March 2006
- Manuscript approved:
20 March 2006
- Version of record:
20 February 2007
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