Abstract
Natural fractures are present in many oil and gas producing reservoirs and largely contribute to the productivity of those reservoirs. Natural fractures, however, also complicate drilling, completion, and/or work-over operations. Hydraulic fracturing treatments are particularly sensitive for the presence of natural fractures as the hydraulic pressure may open the natural fracture system as well as the induced fractures resulting in additional (unexpected) fluid leak-off and consequently early screen-outs.
Recent advances in pressure decline analyses of injection tests have provided the industry with a tool to recognize the presence of natural fractures. However, guidelines on how to design a hydraulic fracturing treatment once the natural fractures have been identified are lacking. The paper presents analysis of hydraulic fracturing treatments in naturally fractured reservoirs conducted in Algeria and Southern North Sea. The treatments analyzed include treatments that were completed as designed as well as treatments in which as little as 10% of the designed proppant amount was placed. Guidelines are proposed based on the commonalties that were found in these analyses.
