Improving Hydrocarbon Recovery Efficiency Utilising Horizontal Production and/or Injection Wells

Abstract

Horizontal wens have seen a dramatic rise in the range of applications and the number of wens completed during the past decade . However, horizontal wens have been primarily drieled as producers maximising tee benefit from the large reservo ir contact which such boreho les allow. To date there have been only a handful of repo rted applications of horizontal wens as injectors . The potential benefit of horizontal injectors could lie in improving the sweep efficiency and enhancing the degree of pressure maintenance characteristics of reservoirs as they enter an advanced stage of depletion in redevelopment projects .With the above in mind the Horizontal Well Technology Unit in Edinburgh has been conducting a two year research programme looking at the potential for improving hydrocarbon recovery efficiency using horizontal injectors, with the overall aim being to establ ish a sound business case for the utilisation of horizontal injection wells. The investigation has concentrated on botte water and gas injection . The first part of the study use d a box type rese rvoir simulation model, to compare horizontaI and conventional vertical injection wens in different depositional environments .Horizontal water injectors veere found to improve sweep efficiency and achieve production acceleration in certain reservoir environments . These inciucted extreme permeability distributions (fining upwards/downwards in rock properties) and high viscosity oils . Higher NPVs veere achieved in these cases .For gas injection, it w as found [teat, because the high mobility ratio completely dominated tee displacement process, improvements in recove ry veere limited .In the third phase of the project, the focus switched to applying the technology to real North Sea field datasets . The studies have confirmed the conclusion from the Barlier work that horizontal injectors seem to function best in love permeability environments due to the much superior injectivity . In higher permeability environments, viscous driv ing forces can lead to increased recovery in favour of vertical injectors. Introduct i onAt the start of this two year long project (January , 1995), there veere few field developments relying on horizontal injection wens and a pancity of description of their performance in the l i terature . This prompted the study to investigate the reservoir env i ronments/conditions in which horizontally completed injection weíls would perform better than conventional vertical in jectors in terms of ultimate oil recove ry , rate of recovery and resultant net present value (NPV) . The work was undertaken in three p hases : model validation, theoretical sensitivities and study of actual fields . In all cases, where possible, the numerical simulation results veere checkel against analytical calculations .

Horizontal Water Disposal Well Performance in a High Porosity and Permeability Reservoir

“…The use of horizontal wells for productivity enhancement is well known and while still somewhat rare, horizontal injection wells have been proposed and implemented in a wide variety of applications (3)(4)(5)(6)(7) . As part of an on-going effort to improve injection capacity of the disposal wells, fi eld trials involving four horizontal water disposal wells and four propped hydraulic fracture vertical disposal wells were conducted.…”