Conformance and Sweep

Produced water reinjection usually cannot be viewed strictly as a disposal operation. It is often an economic component in providing pressure maintenance or drive, and this is not just in high permeability situations. For example, Ovens et al, 1997, discussed water injection in the Dan Field. The reservoir is located in Tertiary Danian and Cretaceous Maastrichtian chalk formations, which are characterized by high porosities (20-40%) but low matrix permeabilities (0.5 - 2 md). The highly porous D1 zone overlies a tighter D2 followed by the higher porosity Maastrichtian units M1 through M4. "In the case of low permeability reservoirs, it is possible to create large fractures, the size and orientation of which can have a profound effect on sweep patterns, producer placement and reservoir management."

Firm evidence from the later drilling of production wells indicated that fracturing had taken place (during a water injection pilot program) in both the Maastrichtian and Danian units, highlighting the need for fracturing models that can account for vertical growth and varying material and fluid transport properties. An extensive field monitoring program was carried out in addition to the development of new fracture prediction models. "With water injection above fracturing pressure, the problem is compounded by long term injection causing changes in reservoir pressure and stress, which in turn couples back to the fracture growth criteria. Some commercial PC scale packages for fracture growth include this effect, but since their software architecture is primarily aimed at fracture stimulation, in the case at hand the use of these packages becomes clumsy, since some of the matching variables, such as swept zone width, would have to be computed separately outside each history match run. For this reason, the field data were matched using simple models of fracture growth, elaborated as required to compute the matching variables, such as swept zone width, measured in the field."

<History Previous History   All associated, nearby injection and production, as well as injection activities in the target well impact future perforamance.
Differences From Stimulation Models

An Introduction to PWRI Models

PWRI Models
  Beanup> Bringing on Line   Performance of an injector is commonly impacted by methods that you practice for mitigation even before full-scale injection activities.

Types of PWRI Models

Audit of PWRI Models

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