Abstract
This paper explores the application of two techniques to rate and pressure transient analysis of fractured wells in tight reservoirs. The first one is the Linear Flow Volume (LFV), defined as a region with size determined by a characteristic distance proportional to but smaller than the radius of investigation. Similarly to it, this distance and the LFV increase with time without dependence on flow rate or pressure. The LFV can be calculated analytically for an infinite linear system. It can also be calculated in terms of cumulative production, pressure change and compressibility. When calculated this way, it gives results that are useful to characterize the well and reservoir before and after linear flow. It gives fracture storage volume for early time and reservoir volume when there is boundary dominated flow. It can also be used to help assess whether there is a closed or open boundary condition. The second technique is a normalization method for tests with variable pressure and flow. This is an alternative to the conventional approach of using p/qB with equivalent time (Q/q) as normalizing variables. The alternative technique is simple and provides normalized variables with much less noise and a better defined straight line in linear flow plots with clear indication of the end of linear flow when present. More importantly, it retains dependence on actual production time as opposed to equivalent time. This eliminates distortions caused by the use of equivalent time. The combined use of LFV and the alternative normalization technique provides an improved methodology for analysis of fractured wells in tight reservoirs. Validation with simulated examples is presented and application to actual cases is discussed.
