As of February 2014, Staatsolie operates 1560 active wells mainly with Progressive Cavity Pumps (PCP) for artificial lifting of heavy crude oil of averagely 16°API. These pumps are installed at an average depth of 1000 feet, producing crude from unconsolidated Tertiary sand reservoirs. Average pump life time of 2 months up to 25 years have been realized with these PCP's. Optimal operation of these PCP's requires sufficient submergence in liquid to prevent the pump running dry and causing early failures. To achieve maximum pump life time, a minimum wellbore annulus liquid level between 50 to 100 feet above pump intake is applied to avoid partial cavity filling problems and dry running of the PCP.
The liquid levels in the wells are mainly acoustically surveyed. Significant challenges in well optimizations to achieve optimal well production conditions at the lowest submergence level were experienced with a foamy liquid column in the annuli resulting into apparent high flowing bottomhole pressure (FBHP). The application of downhole pressure gauges started in 2005 with the main objective to increase the reliability of actual FBHP based on downhole memory and surface read out pressure sensors. Main disadvantage of the memory sensors was the required well intervention jobs to retrieve the gauge to download the recorded data, while surface read out downhole pressure sensors had the advantage of real-time data availability. With the development in downhole pressure sensor applications, smart well operation was initiated in 2011. A smart well at Staatsolie operates around a preset target fluid level. This is achieved by automatic regulation of the pump speed via a variable frequency drive. Smart monitoring can be done locally as well as remotely through an online interface option. Both monitoring methods have the possibility of automatic shutdown control once enabled. The smart application focused mainly on the effective control of the PCP speed to prevent downhole pump failures caused by running dry of the pump and the possibility in achieving optimized production.
This paper intends to cover the experienced operational challenges, advantages and disadvantages based on the testing of different smart well technologies in the Staatsolie heavy oil fields.