Developed in 2013, The Duri Area-13 steamfloodcovers a total of 145 patterns. Patterns are developed as inverted seven spot with 5.5 acres spacing which is the smallest pattern size in the Duri field. Steamflood was started in April 2014 with a single sand target. After 2 years of injection, the production response was less than forecasted, predominantly caused by low injectivity and inefficient drainage.
Steamflood management in Area-13 is quite complex since the zone of interest has lower sand quality compared to the analog areas. Increasing the injection rate has been a challenging task to perform. Most patterns are injecting at 100-250 BSPD at the maximum wellhead injection pressure. This is far below the target injection rate of 800 BSPD. Injection of steam at a low rate is likely to cause steam chest collapse before it reaches the edge of the pattern. Heat losses during steam propagation will reduce steam enthalpy to a liquid phase value. The presence of liquid phase may lead to reservoir pressure increase which causes further injectivity problems.
A pressure balance strategy was initiated in early 2016 to solve this low injectivity problem. Pressure depletion after production withdrawal is promptly balanced by increasing injection. The initiative consists of an integrated effort between production and injection including an aggressive huff & puff strategy, vigorous injector wellhead pressure monitoring and injection optimization.
The initiative has proven to be successful in improving the performance of Area-13, with production and injection ramping up significantly. Current production is higher than the 2017 forecast. The initiative also proved that implementation of a pressure balance strategy between withdrawal and injection could significantly improve injection of a low injectivity steam flood reservoir.