Contending with declining waterflood efficiency

Xinjiang Oilfield Company, one of the largest units of PetroChina Company Ltd. (CNPC), is the largest petroleum-producing enterprise in Western China. Operations include several mature fields that are producing at high water cut after many years of waterflooding. As a proponent of developing and applying new technologies to improve production efficiency, Xinjiang was investigating how to raise recovery in one of these fields, the Huoshaoshan oil field in the Junggar basin. Consisting of hundreds of wells, the field had developed irregular flood patterns after decades of production. High reservoir heterogeneity and extensive layering and faulting compounded the challenge to optimizing recovery.

Several solutions had previously been tested by CNPC Xinjiang’s experts to reduce water cut without reducing oil production. However, most of these solutions were time consuming and difficult to conduct or cost prohibitive, whereas the methods that were easy to implement worked only temporarily or inconsistently. Using a traditional manual workflow was taking the field technicians more than a month to update the injection allocation for all injectors in the field.

Optimizing the waterflood: Successful field trials

The combination of Schlumberger software technology and consulting expertise and collaboration with CNPC Xinjiang’s experts improved the performance of the pilot area wells over the ensuing quarters of operation. The PFM approach made it possible to reduce water injection in more than 50% of the injectors while more than 60% of the producers experienced increased production and reduced water cut. The concurrent productivity of the asset team notably increased upon automation of the workflow for the identification of optimal injection allocation factors. The efficiency gain from automation was significant, delivering what typically took over a month in just under a week.