the injectant passes through a limited number of slots in a base pipe is deflected into an annulus between the base pipe and a screen or the like and passes through the screen into the reservoir on production hydrocarbons pass from the reservoir through the screen into a compartmentalized annulus the screen limits entry of particulate matter the hydrocarbons then pass through the slots in the base pipe and into the well where a screen is damaged the compartmentalization and the slots in the base pipe limit particulate matter entry into the well application_number US 201113102322 A description the term u201c viscous oil u201d as used herein means a hydrocarbon or mixture of hydrocarbons that occurs naturally and that has a viscosity of at least 10 cp centipoise at initial reservoir conditions viscous oil includes oils generally defined as u201c heavy oil u201d or u201c bitumen u201d bitumen is classified as an extra heavy oil with an api gravity of about 10 u00b0 or less referring to its gravity as measured in degrees on the american petroleum institute api scale heavy oil has an api gravity in the range of about 22 3 u00b0 to about 10 u00b0 the terms viscous oil heavy oil and bitumen are used interchangeably herein since they may be extracted using similar processes u201c in situ u201d is a latin phrase for u201c in the place u201d and in the context of hydrocarbon recovery refers generally to a subsurface hydrocarbon bearing reservoir for example in situ temperature means the temperature within the reservoir in.