# PPT Slide

Layered formations

- Water injection for disposal and / or voidage replacement / sweep

- Injection above frac pressure: Difficult to control where frac goes

- Ample evidence of frac containment by ‘non-classical’ mechanisms (not covered by current models)

- E.g. Mat. Property differences, interface slippage, tip screen out at interface, others ...?

- Impact on sweep, injectivity, ..

- Role of contaminants?

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