Abstract
Prehydraulic fracture diagnostic pumping analysis has recently improved with the use of new analysis techniques such as G-Function derivative plots, after-closure analysis, and step-rate tests. This paper analyzes various types and combinations of step-rate injection tests from many different formations around the world to determine the usefulness of these tests. The analysis uses wells with both surface and bottomhole gauge data, and in some instances, compares the results of the two. The final results of the stimulation treatments are also compared to the prefrac analysis. While the results of these tests provide information on the presence of excess near-wellbore friction or tortuosity, what is often not taken into account is that this tortuosity often destroys the usefulness of these step-rate tests in providing much sought-after data such as accurate fluid efficiency and closure pressure numbers.
The focus of this paper will be on step-up and step-down analysis, with the result being a new type of graph that provides an indepth look at the quality of these tests in any given well. Often these tests are performed and erroneously analyzed because of the effects of tortuosity, with the end result being either the data is ignored or discarded. Techniques are provided for analyzing these tests and suggestions are given to improve the results obtained from these tests.
