Currently, a significant quantity of oil fields all over the world are developed with reservoir pressure maintanance mechanisms.

It is worth noting that sometimes water is injected into a reservoir with pressure, which is higher than the rock pressure. Such condition causes technogenic autofracture opening in productive layer. The autofracture is not strengthened with a proppant, so its geometrical size changes with the change of bottomhole pressure. And this feature leads to some difficulties with injection well work regulation.

An attempt to explain the reasons of ineffective well operations (bottomhole treatment and outflow profile alignment) on several fields of West Siberia was an occation for these studies. We found a considerable number of examples on these fields, where well operations had opposite results than were expected. So, we have hypothesized the causal link existence between holding ineffective well operation and the presence of autofracture in this injection well. For this aim, first of all, we describe the algorithm for autufracture detection in injection wells with the help of Bourdet diagnostic plots (which are used in well test interpretation) in conjunction with field data. Then, we checked our hypothesis by studying a statistic correlation between well operations with opposite result and autofracture presence. Finally, we show an explanation how opposite results of well operations in injectors with autofracture can be easily explained. The reason is rather obvious, but this phenomenon have never been described before: all the matter is in ratio between bottomhole pressure and pressure of autofracturing before and after well operation.

Based on these results, we made a clear conclusion about the necessity of considering possibility of autofracture appearance in injection wells. Also we will give some recommendations about work regulation for injection well with such feature.

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