Apparent fracture conductivities measured in Germany were 80% lower than the reference values due to non-Darcy flow. Apparent fracture lengths were approximately 50% of the designed length. Production forecasts which ignore non-Darcy effects will be unrealistically optimistic.
The low-permeability (1 to 100 mu d) sand members of the Rotliegendes and the Carboniferous formations are a major source of gas reserves in West Germany. To establish commercial production from the limited number of deep (+13,100 ft [+4000 m]) Rotliegendes and Carboniferous wells drilled to date, stimulation of the wells with massive hydraulic fracturing (MHF) treatments is necessary. A great deal of effort was directed not only at the design and performance of these MHF stimulation jobs, but also at the interpretation of buildup data obtained from the treatments and at the integration of the results into a model for future production forecasts.
This paper reviews the available hand-applied methods used to analyze the postfracture behavior of wells stimulated with the MHF technique. These methods analyze buildup data collected during the past 5 years from three wells, each producing from more than one horizon. The results of these analyses include the length and conductivity of the fracture created during the MHF treatment.
Author(s): K.M. Reinicke, BEB Gewerkschaften GmbH; F.W. Brinkmann, BEB Gewerkschaften GmbH; Heinrich Schwarz, BEB Gewerkshaften GmbH; Greg Hueni, Bergeson and Assocs.
Paper Number: SPE 11605