Daleel Petroleum increases output of crude oil shipping pumps by 45%

London – WEG Middle East has supplied 250kW HGF motors to fit in the same space envelope previously occupied by three 132kW Loher pump motors, at the Daleel Petroleum Oil Field in, Oman.

The kit is enabling Daleel Petroleum to increase the output of three crude oil shipping pumps by 45% respectively; each pump now being capable of shipping 16000 bpd, instead of 11,000 bpd previously.

This increase also offers the advantage of enabling one pump to be withdrawn at any time for maintenance, without Daleel Petroleum incurring penalties for falling below its contracted pumping rate of 30,000bpd.

Located in a remote area of Oman, the Daleel Petroleum Oil Field is responsible for a series of exploration and production wells. The crude oil is collected via a series of pipelines and manifolds, treated to remove water, sand and salt, to meet the specification set by Petroleum Development Oman (PDO), and then stored in large tanks. The next stage of the process is to pump the oil from the storage tanks to the PDO pipeline network; this is the task of three crude oil shipping pumps, which until recently were running at close to full capacity in order to meet production targets.

Currently the agreement between Daleel and the Petroleum Development Oman (PDO) stipulates that Daleel has to feed 30,000 bpd (barrels per day) of crude oil into the PDO pipeline. Until recently, this figure was achievable only by running all three of Daleel’s existing crude oil pumps three pumps at the same time (providing 33,000 bpd maximum) Unfortunately, this ’full-on’ operation posed risks to production, as it was not even possible to stop one pump set for maintenance, for example, without incurring financial penalties.

Pump supplier, Flowserve, was asked to look at this problem with a view to uprating the crude oil pumps, to enable Daleel to meet its daily pumping obligations, and have capacity to spare, by using just two pumps at any one time, instead of all three.

A number of major motor manufacturers, WEG among them, were invited to submit proposals and tender for the project, which involved providing larger motors for each pump (250kW), together with variable speed drives and control equipment built into panels.

The project was complicated by the customer demand that the existing 132kW pump motors be replaced by 250kW units, whilst maintaining basically the same dimensional envelope, to simplify installation. In addition, the requirement for the three motor and VSD control packages was urgent, and so delivery time was a crucial element in determining which supplier would secure the order.

According to WEG, it was the chosen supplier, due to the engineering support it provided, plus a faster delivery time and the security to the customer of a 3- year warranty on the motor and VSD packages supplied.

The WEG package comprised 3 - 250kW, 315C/D/E HGF 2 -pole motors, plus three CFW-09 variable speed drives assembled into control cabinets. The panels housing the VSD are located 150m away from the pump motors in an electrical control room where the temperature can be controlled, usually below 30ºC, even during the summer when temperatures outside may reach 55ºC.

In addition to the panels, the control room also houses load reactors, which were also supplied by WEG. These are required to compensate for the capacitive effects of the long cable runs between the motors and inverters.

The electrical installation for the first motor provided a pattern for the subsequent two installations, enabling a host of tasks to be undertaken in advance before the two other panels arrived in the site.

After the complete installation of the first motor and its associated panel/VSD, the HGF motor was run uncoupled without load for 24-hours. Once this period had elapsed, WEG coupled the pump to the motor and started another 24-hour test run, this time simulating a real operation.

When this test was concluded the motor continued in normal operation, providing much improved pumping performance of up to 16,000bpd compared to the 11,000bpd available from the original pump sets.

To-date, two of the three motors and its VSD control panels have been installed and are enabling Daleel to meet its daily pumping capacity even before the final motor package is installed. The new motors – unlike the one’s they replaced, which had DOL starting – offer soft start characteristics as well the far more controllable operation provided by VSD.

Commenting on the Daleel application, Luciano Rottava da Silva, WEG’s field engineer for the project said: “The climate in Oman is so hostile - ambient desert temperatures that regularly exceed 500C in the hot season; plus frequent sand storms - that it’s critical to have rugged, low-maintenance motors, variable frequency drives, and control packages capable of reliable and repeatable performance.