Case Studies

EOR Well – CO2 Shut-Off

EOR programs utilizing CO2 experience significant problems with leaving bypassed oil in the ground due to CO2 fingering from injector to producer. The operator did an evaluation of available autonomous concept, and selected the Autonomous Inflow Control Valve (AICV®).

Objectives
Gain economic advancements for the EOR scheme using CO2 and water injection but use of applying AICV® and ICD (multi-position) technologies to reduce GOR (Gas Oil Ratio) and increase Oil Production.

Approach

The new technology deployed involves integrating an autonomous inflow control valve (AICV®) and a conventional (passive, non-autonomous) inflow control device (ICD) into a unique 3-position “sliding sleeve”, shifted by coil tubing, to allow performance comparison between the two different inflow control devices as well as multiple flow control settings of each type. The AICV® was designed (and lab tested) to selectively choke back or shut off flow of free CO2 gas and also high watercut (>99%), thereby
significantly improving reservoir sweep and yielding higher oil production. The AICV® opens or closes autonomously depending on sensed properties of wellbore fluids. Prior to installing the advanced completion, the multi-zone (vertical) trial well was extensively characterized using PLT and other log data, which was then inputted into a commercially available computer model to help design the AICV® and ICD settings. The field trial was designed to evaluate the use of flow control in the EOR scheme over a
wide range of flow rates and also to compare the two different flow control technologies at different settings within the same wellbore and reservoir conditions.

Result
AICVs have the ability to autonomously sense unwanted fluids and then shut off their flow until wanted fluids migrate back to the wellbore. Furthermore, AICVs can perform optimally without the need of expensive PLT data to pre-adjust their settings. This indicates a significant advantage over conventional ICDs.

Furthermore, AICVs can be designed for a wide range of fluid properties and shut-off objectives.

Figure 1

Well performance summary - AICV's only vs. no-ICD

Reference page 22, table 7 within SPE 181552.