Abstract
Drilling horizontal wells is a standard practice in the oil industry. Placing hydraulic fractures along the horizontal section of the well, to increase hydrocarbon production, is also rapidly gaining popularity, especially as more tight formations, even shale, are targeted. Understanding the behaviour of each individual fracture requires production logging. This results in additional cost and also puts the well under "operational risks".
It is desirable to use pressure data to understand the well behaviour, as this is readily available due to modern completions usually having permanent pressure gauges installed. Also, pressure data can be obtained without putting well at any "operational risks". In the region around fractured horizontal well, multiple flow regimes occur simultaneously. In pressure transient data usually a combination of all the flow regimes is observed making characterisation of the reservoir difficult.
In this paper, a comparison of the existing analytical approaches is made to analyse pressure transient data for a horizontal well intercepted by multiple fractures. Using the analytical solutions of the diffusivity equation presented by different authors for a multiply fractured horizontal well, the dimensions of Stimulated Reservoir Volume (SRV) are calculated. Also, the number of active fractures and the flow rate from each fracture are determined using the pressure data. The time for the start of interference is calculated and the time dependence of individual fracture flow rates is also estimated. An observation about the inability to find the orientation of fractures is also made.
