Test separator is an important part of surface well testing system. Test separator separates fluids and gases coming from well head into three phases, gas, oil and water. The task of well test operation is to receive data of flow, pressure, temperature of each phase, as well as getting samples of oil and gas. So test separator skid shall at least consist of one gas meter, one oil meter and one water meter. Type of flow meter is chosen either by Buyer or recommended by separators’ supplier, like HC Petroleum Equipment. 

Let’s start with separator vessel which is horizontal or vertical pressure vessel with certain internals to increase separation efficiency. Size of separator vessel influences the cost price. The bigger and longer the separator vessel, the heavier it is. Subsequently, more steel and more welding works are required. Another important factor is design pressure. Most test separator are designed for 1440 psi pressure rating. The more design pressure, the thicker vessel wall shall be, and for higher pressure valves and instruments shall be designed, which is also increases the cost price. Most common sizing for pressure vessel is 42” x 10’. Some client may require smaller diameters like 36” or 30. Some clients, require bigger diameter like 48”, 72” 84”. So operator shall make sure what size and what pressure for separator skid is required. Second, operator shall specify required code & standards, certification for mechanical part Is required. 

But separator vessel, which is mechanical part, is not main price influencer. Valves and instruments of separator skid or separator module, whatever it is called, significantly influences the price. Let’s start with gas line. Usually, separator equipped with one 4” or 6” orifice plate & fitting. Some clients may require two orifice plates in one separator skid. 3” & 6” Orifice fitting. The more flow meter is added, the more gas line components increase because besides orifice plate, separator’s gas line includes chart pen recorder, thermowells, gauges, ball valves, pneumatic control valve, pressure controller. So client shall clearly specify number of gas lines required and composition of each line. Some operators, may require Coriolis type gas flow meter, which comes in 2”, 3” and 4” sizes. Type of gas flowmeter, and gas line components influences the price of separator skid. 

Liquid outlet lines, oil and water, usually consists of two oil meters, and one water meter. Type of liquid flow meter is turbine, while some client may require Coriolis liquid flow meters. HC had participated in the projects, where client wanted turbine and Coriolis flow meters in one oil line. Oil line has minimum number of flow meter, which is one, while maximum number of turbine flow meters is three. Water line usually consists of one or two turbine flow meters. But like in oil line case, water line can be equipped with Coriolis flow meter. So liquid outlet lines may consist of small number flow meters and big number flow meters. Each effecting the cost price of separator skid. 

As a safety measures, each separator must be equipped as minimum with one relief valve and one rupture disc. Some client may require two relief valves. Type of relief valves also influences the cost price. Spring relief valves are cheaper than pilot-actuated relief valves. Pilot-actuated relief valve usually used in hydrocarbon processing plants, where gas may flow backwards, and Spring-type relief valve may be not that effective in backflow situation, while pilot-actuated relief valve is not susceptible to backflow. 

Control valves and level controllers another set of separator components which also influence cost price. Type of level controllers and pneumatic control valves shall be specified by buyer during sending RFQ to the Vendor. Most test separators are designed to mechanically control gas pressure and liquid levels, while fully digital control system is also available. In the most domestic projects, HC Petroleum Equipment supplied digitally controlled separator skids. In this case, all control valves have positioner which is connected to PID Controller, which receives signal from level transmitter. Also, all flow recording items are digital, recording data in computer software. For international projects, client require mechanical control system with mechanical controllers, and chart pen recorder. Type of control and data acquisition shall be informed to the Vendor before asking Vendor to provide proposal and pricing. 

The most important price-influencer in HC’s practice is brand of components. Chinese and famous brand components may differ in price significantly increasing cost price from 100 to 200%. HC Petroleum Equipment offers good combination between Chinese brand and famous world brand components. For example, for flow measurement, we recommend to use famous brand meters and recorders, while for valves and instruments which only displays (indicates) data, we recommend to use Chinese brands, as some Chinese components have the same quality as products of western suppliers. HC has several experience in working with similar overseas projects and it proofed it is workability. 

When it comes to making final decision by the client, clients always hesitant to work with Chinese separator suppliers, while HC can offer same quality performance as other suppliers. There are significant misunderstanding between buyer and seller during price review. If the buyer has certain target price, buyer shall put it forward and discuss with vendor directly and open-mindedly. In this case, both buyer and seller will be developing solution which suits both budget and requirements to separator performance.  HC Petroleum Equipment is capable to design and fabricate world-standard test separators and well testing equipment, meeting both client’s expectation for price and performance. Feel free to contact HC Petroleum Equipment for technical assistance and ideal solution for test separator skids and other surface well test equipment. 

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