Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, October 1--December 31, 1997

Abstract

This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically fractured horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan-margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation is used to select the well location and orientation. Design parameters for the hydraulic-fracture treatments are determined, in part, by fracturing an existing test well. Fracture azimuth is predicted by passive seismic monitoring of a fracture-stimulation treatment in the test well using logging tools in an offset well. The long radius, near horizontal well has been drilled. Swept-out sand intervals and a poor cement bond behind the 5 in. liner precluded two of the three originally planned hydraulic fracture treatments. All pay intervals behind the 5 in. liner were therefore perforated and stimulated with a non-acid reactive fluid. Following a short production period, the remaining pay intervals in the well, behind the 7 in. liner, were then perforated. The well was returned to production to observe production trends and pressure behavior prior to stimulation of the newer perforations.