WAG Switchover Automation Transformation Towards Realizing Remote Operation
Authors: Sahak Muhammad Zakwan Mohd , Mat Tengku Amansyah Tuan , Thant Maung Maung Myo , Castillano Eugene , Law Hiu Ying , Harun Zalina , Razale Nur Atikah 
Published: October 2023

Water-alternating-gas (WAG) injection is widely used to further improve the recovery for oilfields, on top of secondary recovery methods e.g. water or gas injection. During WAG injection, water and gas will be injected in alternating sequence i.e. water is injected at predetermined rate for certain duration, followed by gas injection, and continuously alternating between water and gas periodic injection until the target oil recovery is achieved. Current practice of manual operation for switching between water and gas injection based on standard operating procedure (SOP) can further be enhanced via automation. In this case, a procedural automation can be adopted to ease the operators’ action and standardize the switching rate procedure. Automation of routine operation is considered as critical elements for digitalization of oilfield, preparing the basis for full scale remote operation.

First, review of the current SOP was carried out to identify critical steps from the WAG switchover process. These series of interrelated steps were grouped into a larger module, which will be used for triggering different phases of the switchover. Next, development of programmable logic sequence based on SOP consisting of three main elements for each step: Command, Perform and Verify. This will enable each step to be carried out and action is verified before moving on to the next step. Lastly, process simulation was conducted to assess the effectiveness of the newly developed process control scheme and to optimize its operating envelope further.

Procedural automation logic was developed for switchover based on the SOP used by operator for manual operation. The main steps involved are pressurization, valves switching and injection ramping. Process simulation conducted showed that the logic developed was running based on the intended sequence, with verification steps to determine when to proceed to the next step. With procedural automation, reliance on manual operation for WAG switchover process is reduced resulting in less human-error and HSSE risks. A more standardized approach can also be realized by capturing both the know-how from operating procedure and operational experience from operators into development of the automation logics.

Challenges and lesson-learnt from transforming the manual SOP into procedural automation logics were discussed. This paper describes the high-level concept and key design consideration in transforming manual WAG switchover operation into automated operation in Malaysian oil field for improving the hydrocarbon recovery. It also describes step-by-step approach for the technology development and adoption for potential replication to other system and field. This technology was developed as part of the overall injection system automation improvement effort covering water, gas and WAG injection, serving as the big picture component of oilfield digitalization and remote operation.