29-08-2017, 10:24 AM
Heavy oil production from shallow wells using rod pump applications requires careful design considerations, especially for downhole components to achieve maximum production rate and maximize life. This paper highlights a successful case study of one of these heavy oil pumping pumping wells at the Kuwait Oil Company (KOC) field in northern Kuwait, where the rods were specially designed to penetrate through oil viscous and address the floating problem of the pump to achieve uninterrupted operation of the pump. Conventionally, as a rule of thumb for shallow wells, the rod design consisted initially of twenty percent sink bars and eighty percent suction rods. This was to add weight to the pump for stability and proper balance. In the case of this well, with the same design philosophy employed, it was observed that the pump floated on viscous oil. It was observed that the maximum filling of the pump was less than fifty percent. Finally, operational changes were made by reducing the speed and operating at the maximum stroke length. However this still did not bring any improvement. Therefore, specific design modifications were made to the rod and the size of the pump in order to solve the problem of pump flotation, reach the maximum production speed and operate at the maximum possible efficiency. After the design change, it was observed that the pump was now able to effectively penetrate through the viscous crude. This increased the filling of the pump to 75% consistently, improving the rate of production. It was also noted that it improved the balance of the unit. This well design was considered as part of the pilot in the heavy oil project in the north field of Kuwait. Since the floating pump phenomenon is expected in KOC heavy wells, this design would be used in wells operated with similar suction rods and neighboring wells suffering from the same well conditions. It is expected that by overcoming this operational issue there will be considerable cost savings and improvements in production.