Sometimes the solution to a plant operations challenge isn’t just automating with instrumentation, but rather choosing the right instruments for the job. A major crude oil and natural gas exploration and production company was experiencing problems with their level measurement in heater treaters. The company was unable to optimize their heater treater separators, which were causing gas to be carried over to the tanks, a very costly loss. This was a significant problem for a major production company operating in the Bakken Oil Field located in the U.S. and Canada, producing over 4,800 MBOE.
Previously, the company used mechanical valves for level measurement, but they did not perform well to solve the problem. The customer was looking to replace these traditional mechanical instruments in order to more efficiently operate their heater treaters. Their goals were to improve level measurement, minimize lost production while maximizing production and yield, and reduce emissions. The main concerns were: improving efficiency of the heater treaters; optimizing liquid level control; and reducing gas carryover to the tanks.
Meeting these goals began with an informative false start. Initially, traditional DP level transmitters were fitted to improve liquid level measurement in the heater treaters. However, the traditional DP needed the wet and dry legs to be blown out regularly otherwise the readings could be affected – a historic characteristic of DP transmitters in some applications. The technology was also not easy for the operators to understand – a problem in an industry where many experienced workers are retiring, and new personnel lack the same hands-on expertise with instrumentation.
The customer retrofitted their existing tanks using Rosemount™ Electronic Remote Seals (ERS) on the oil and water legs, replacing the traditional DP transmitters. The ERS system was much easier for operators to understand than the traditional DP. The ERS system also had no wet or dry legs requiring maintenance, thus significantly reducing personnel time. In addition, it provided faster response time than traditional differential pressure transmitters.
The company also wanted to take advantage of the ability of guided wave radar to measure level, and interface with a single device in new separators they were building. Since the new installations were not constrained by the tank configuration, their manufacturer added a 4-in. (101.6 mm) stilling well inside the separator to accommodate a Rosemount 5300 Guided Wave Radar. This simplified installation even further. The installation using the guided wave radar in the stilling well was efficient and cost effective.
Results exceeded the company’s requirements. The combined ERS DP measurement and guided wave radar resulted in accurate flow and liquid level measurement and reduced gas carryover, which in turn led to increased efficiency. The company measured a reduction in gas carryover from 140 mcf to 60 mcf. The guided wave radar has a low operating cost because it requires minimum maintenance. Using the Rosemount 5300 to control the oil and water levels in the treaters also eliminated the requirement for piping and additional tanks associated with the test treater, resulting in savings of $30,000 per train. Gas carryover was also significantly reduced, with possible savings of around $100,000.
What type of level measurement do you use? Do you feel it maximizes your efficiency?
In reply to SteveWJ:
In reply to Tom Wienke:
In reply to KeeChong:
Anshuman Prasad
Director of Integrated Marketing, Rosemount Measurement and Analytical