Abstract

Over thousands of fracture treatments have been performed in the Antrim Shale of Northern Michigan. Very few have been altered sighificantly based on pressure data acquired from each preceding treatment. In essence, there has been very little evolution in how operators stimulate the Antrim. Primarily, this is due to the inability to accurately model (fracture) the effect of natural fractures in the Antrim Shale. Nevertheless, it is possible to use these models to analyze pretreatment pressure responses to produce a more efficient frac design and improve the resulting frac conductivity. As the industry moves away from the "cookie cutter" frac design towards one specifically design, with minimal additional time and effort, for the well, a mere 10 mcI/cl/well increase in production over a poriod of 10-15 yrs becomes very economical.

This paper will illustrate simple diagnostic tests that can be performed prior to each fracturing treatment to give good indication of fluid efficiency localized rock stress. Under real-time cicumstances, a 10-15rnin injection test folliewed by a complete fall-off can yield an abundance of information regarding the viability of a particular fracturing treatment.

In the Antrim Shales on Northern Michigan, these diagnostic techniques have been used successfully to determine leak-off, closure, fracture extension and various other parameters essential in designing a fracturing treatment. In addition, pre-treatment results have been linked with the success or premature screen-out of particular wells in the Antrim.

Through case studies, this paper will show a logical progression of data analysis based on diagnostic results. Resultantly, a fracturing treatment can be designed or altered on location based on actual reservoir response and measured stresses. In turn, operators can regain a measure of predictability in controlling fractured behavior by tailoring a unique solution for each well without excessive time or added cost.

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