Research aspects for the Liquid Addition to Steam for Enhancing Recovery (LASER) process were described in a previous paper(1). The research concept has since been field-tested for a single cycle at a pad at Imperial Oil's CSS (Cyclic Steam Stimulation) operation at Cold Lake. The pilot entailed the addition of a small 6% volume fraction of C5+ condensate (diluent) into eight wells during CSS Cycle 7. The key pilot objectives were to assess:
the increase in oil-steam ratio (OSR) over CSS; and,
the level of diluent recovery.
The overall performance of the pilot to date has been encouraging. The diluent recovered is estimated to exceed original expectations and is similar in composition to the injected diluent. The increase in OSR was consistent with original expectations.
Suites of monitoring instrumentation and analytical methods were developed to allow quantification of the recovery of injected diluent. In addition, multivariate analysis (MVA) statistical methods were used to develop a model of CSS process performance. This model reduced the statistical background performance ‘noise’ associated with normal base CSS operations and allowed an improved analysis of the OSR increase in the pilot to be made.
The LASER process has been described in patents issued recently in both the US and Canada(1). It essentially consists of combining thermal and solvent effects in a cyclic mode of operations to improve CSS performance. The preferred solvent for LASER is diluent that is already used to pipeline produced bitumen to markets. In cyclic-type operations, the mixing and contacting of solvent with targeted bitumen is expected to be more effective than in continuous thermal operations conducted at constant pressures.
Background information on LASER technology has been described previously(2). This background includes:
a description of both CSS and LASER processes for Cold Lake;
the laboratory physical proof of the principle for the LASER process;
the validation of that potential using single-well numerical simulations; and,
a brief outline of the LASER demonstration pilot scope and design facilities.
The primary objective of the field pilot was to collect sufficient high quality data to allow an accurate assessment of key performance indicators such as:
bitumen production increase; and,
Based on the initial simulation work conducted with 6% volume ratio of diluent in steam, performance expectations were for an OSR increase of 33% over CSS and a recovery of 66% of the injected diluent.
Currently, Imperial Oil produces approximately 22,260 m3/d (140,000 bpd) of bitumen using the Cyclic Steam Stimulation (CSS) process from its Cold Lake field in east central Alberta. The process is expected to recover approximately 25% of the original bitumen in place (OBIP). Previous work has indicated that, if successful, the LASER process could increase this recovery factor by 3 – 6% OBIP.
Pilot Location Selection and Well Layout
The H22 (LASER Pilot) and H21 (CSS Control) pads are located in the northwestern area of Imperial's operations at Cold Lake.