Layered Formations

The best practices, guidelines and summaries that are available, include:

Background Everyone tells you about the complexities of injecting into layered "reservoirs," i.e., concurrent injection into one or more formations or zones in a formation with differing properties. What are the general issues that you would have to consider?
Crossflow: One of the most difficult issues to deal with is crossflow. This is movement of fluid from one formation or zone to another, either through flow in the wellbore or with a component of flow in the reservoir that is not "horizontally" through the formation itself. Background about crossflow and tools to assist in forecasting the degree of in-well crossflow are available.
Pressure Transient Evaluations: The industry has developed pressure transient techniques for estimating the transport properties (i.e., permeability and skin, etc.) for multiple zones. A summary of the methods (which generally require concurrent measurement of pressure and rate into the various zones is available. General guidelines are provided.
Mitigation: It is one thing to diagnose problems in layered reservoirs (i.e., you may not be able to achieve adequate conformance), using pressure transient methods, observations at offset producers, and common sense). It is another matter to plan how to mitigate inadequate conformance. Various possibilities are presented that you might consider for improving or maintaining your injection profile.
Intelligent Completions: One method for regulating performance is to install completions that you can adjust so that flow into multiple zones is explicitly controlled by mechanical means without intervention. Intelligent completions (IC), or intelligent well systems (IWS) allow the operator to mechanically regulate injection.
An Example: One well-documented case is presented that shows the difficulties in effectively and consistently controlling injection into zones with differing properties.

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