Microseismic Responses from Two Hydraulic Fracture Stimulation Strategies of One Horizontal Well in a North American Shale

摘要

The goal of hydraulic fracture stimulations in unconventional reservoirs (e.g., shales) is creating an extensive, high- density fracture network. In December, 2010 the ~3050-m horizontal section of a ~3200-m deep well in a North America shale was stimulated using two strategies over a 30-stage stimulation. Stages 1-22 used ball-actuated, sliding-sleeve technology to open pre-existing wellbore casing slots, giving the stimulation fluid access to the surrounding rock; Stages 23-30 used pump-down- perforation-guns-with-plugs technology to deploy the plugs between stage sections and shoot casing perforations, again giving access to the surrounding rock. The whole stimulation was microseismically monitored using one, vertical, 45-level, 2,164-ft long, 3-component geophone array with its deepest geophone package deployed at the approximate depth of the stimulated well. The array recorded 1,388 stimulation-induced microseisms, 519 induced by Stages 1-22 and 869 induced by Stages 23-30. The microseismic data showed (a) the sliding sleeve stages generated sparse; narrow, somewhat-isolated microseismic event clouds, indicating a less-developed, but deeper-penetrating fracture network and (b) the plug and perforation stages showed dense, highly- overlapping microseismic event clouds, indicating a more-extensive, less-penetrating fracture network. In support of these findings, a data set from an unconventional reservoir comparing oil production using the two stimulation strategies from different wells, showed plug-and-perforation stimulated wells substantially out produced sliding sleeve wells.