Enhance Heavy Oil Production of Horizontal Well by Distributed Downhole Electrical Heating

Abstract

Abstract Horizontal wells are widely drilled to produce heavy oil for its large reservoir contact, and the length of horizontal well usually ranges from 100m to longer than 1000m. Up to now, limited attention are attached to flow in the wellbore and vicinity of horizontal well and its influence on production performance. In fact, the influence of flow resistance in wellbore and vicinity of horizontal well on heavy oil production should not be ignored for cold production, and even thermal processes such as CSS. In order to investigate the flow in wellbore and vicinity of horizontal well, rheological characteristic of heavy oil and water mixture are measured at different temperature and water cut, and flow in the wellbore and vicinity of horizontal well and according oil production improvement by distributed electrical heating are investigated primarily based on experimental simulation and reservoir numerical simulation. The rheological measurement results show that more than 50% - 90% reduction in viscosity of heavy oil and water mixture could be obtained as temperature increasing from inflection point temperature (80 - 90℃) to 120℃. Up to 2 - 7 times of fluid production index could be obtained by distributed electrical heating in pipe flow experiment. Both sand paced model experiment and numerical simulation indicate that oil production by distributed electrical heating is 1.5 - 4 times than that of cold production, and oil production by combination of CSS and electrical heating in production period is 1.2 - 2.0 times than CSS. In order to improve heavy oil production in cyclic steam stimulation process, a 1400m long, distributed electrical heater packed in coiled tubing is developed using stainless steel jacked mineral insulation cables. It is successfully installed and soundly operated in a horizontal well in Liaohe Oilfield. As result, about 30% - 50% increase in average oil production rate is obtained by distributed electrical heating, the production period is evidently extended, and approximately 10℃- 20℃increase in wellhead temperature obtained. It is potential to improve heavy or waxy oil production in horizontal well by distributed electrical heating both in cold production and thermal production such as CCS. Furthermore, such coiled tubing packed heater could be used to heat the injected steam to increased the steam quality and temperature, or serves as igniter for in-situ combustion. Additionally, it offers a new way to develop downhole steam generator.