--> Abstract: Role of Stress Field and Hydrofracturing in Enhanced Oil Recovery through 3-D Fluid-Injection, by Kenneth J. Hsu; #90078 (2008)

Datapages, Inc.Print this page

Role of Stress Field and Hydrofracturing in Enhanced Oil Recovery through 3-D Fluid-Injection

Kenneth J. Hsu
Lazarus Oil International, Haslemere, United Kingdom

Artificial aquifers in hydrologic cells can be used in enhanced oil recovery by means of 3-D water-injection, with conventional hydrofracturing to make sets of vertical extensional fractures across two parallel horizontal boreholes. The direction of the horizontal drilling is chosen on the basis of regional stress distribution. The oil reservoir of the EOR system is divided into a series of production strips, which in effect become compartments, so that those strips are sequentially exploited. A first well, drilled into a first portion of the oil reservoir, is for water injection. A second well, drilled into a second portion of the reservoir, is for oil production. Hydrocarbons are driven by injected fluid (water or gas) under a pressure gradient to flow horizontally to sweep the oil of a reservoir in the direction from a source aquifer to a sink aquifer. Each production strip comprises a source aquifer formed by hydrofracturing across the first well and a sink aquifer also formed by hydrofracturing across the second well.

Feasibility studies and computer-simulation models suggest that sweep efficiency can be doubled. Although the technology was invented for EOR of depleted or abandoned fields, it is best applied to newly discovered fields with reservoir-permeability too small to be exploited by conventional technology. A production test at Changqing Oil Field, China, yielded an initial production rate of 280 barrels/day from an oil-bearing siltstone with ~0.1 millidarcy permeability.

This technology (described in US Patent 6,158,517) may also be applicable to exploitation of tar sands and gas hydrates, where hydrocarbons plug the pore space of the host-rock/sediment, so that hydrocarbons can be induced to move vertically across a large vertical cross-sectional area from a source aquifer to a sink aquifer.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas