Category Archives: Mud Gas Separator

Mud gas separator is also called poorboy degasser which designed primarily for the removal of entrained gas, from the drilling fluid. The mud gas separator is designed in multiple capacities, to meet specific mud gas needs.

mud gas separator

The Mud/Gas Separator allows operators to circulate the drilling fluid by removing large pockets of gas. The gas cut mud enters the unit, where it hits a series of baffle plates. These baffle plates provide surface area for the dispersion of the gas cut mud.

The mud is routed to solids control equipment for further processing while the separated gas travels to the flare line at the top of the unit to be vented at a safe distance from the rig and rig personnel.

DC solid control uses high quality steel materials manufacturing normal pressure prevent H2S Mud Gas Separator,can effectively prevent the harmful gas erosion, ensure the man- machine safety production.

DCZCQ mud gas separator is designed primarily for the removal of entrained gas, from the drilling fluid. The DCZCQ mud gas separator is designed in multiple capacities, to meet specific mud gas needs.

DC Solid control manufactured a common model mud gas separator for a India repeat clients who are focus on deep well drilling contractor.


DCZCQ800 Mud-Gas Separator is 800mm in diameter and 6000mm tall, can handle atmospheric operation of200~260m3/h. Its efficient baffling system optimizes mud/gas separation, enabling operators to drill deeper, larger diameter wells and exploratory wells at higher circulating rates while handling greater volumes of gas. It minimizes gas cut mud at the flowline and from an environmental standpoint, it minimizes mist carry-over.

DC Solid control also provides many models mud gas separators, such as DCZCQ600, DCZCQ1000 and DCZCQ1200. So if you have interest please contact me freely.

The mud/gas separator is designed to provide effective separation of the mud and gas circulated from the well by venting the gas and returning the mud to the mud pits. Small amounts of entrained gas can then be handled by a vacuum-type degasser located in the mud pits. The mud/gas separator controls gas cutting during kick situations, during drilling with significant drilled gas in the mud returns, or when trip gas is circulated up.


Three types of mud/gas separators commonly are used today: closed bottom, open bottom, and float type. The principle of mud/gas separation within each type of vessel is identical. Differences can be found in the method of maintaining the mud leg.

Commonly called the poor boy, the open-bottom mud/gas separator is typically mounted on a mud tank or trip tank with the bottom of the separator body submerged in the mud. The fluid level (mud leg) in the separator is controlled by adjusting the fluid level in the mud tank or by moving the separator up or down within the tank. Mud-tank height can restrict the maximum mud leg obtainable for open-bottom mud/gas separators.

DC use high quality steel materials manufacturing normal pressure prevent H2S Mud Gas Separator,can effectively prevent the harmful gas erosion, ensure the man- machine safety production. We provide 4 models of open-bottom mud/gas separator, such as DCZYQ600, DCZYQ800, DCZYQ1000 and DCZYQ1200. Please contact us if you have interest with it.

The height and diameter of a poorboy degasser separator are critical dimensions which affect the volume of gas and fluid the separator can efficiently handle.

As the mud and gas mixture enters the separator, the operating pressure is atmospheric plus pressure due to friction in the gas vent line. The vertical distance for the inlet to the static fluid level allows time for additional gas break-out and provides an allowance for the fluid to rise somewhat during the operation to overcome friction loss in the mud outlet lines.

mud gas  separator

Care should be taken to ensure minimum back pressure in the vent line,. On most offshore rigs, the vent line is extended straight up and supported to a derrick leg. The ideal line would be restricted to 30 ft in length and top of the line should be bent outward about 30 degrees to direct gas flow away from the rig floor. If it is intended that the gas should be flared, flame arresters should be installed at the discharge end of the vent line.

As stated previously, when the gas pressure in the separator exceeds the hydrostatic head of the mud in the U-tube, the fluid seal in the bottom is lost and gas starts flowing into the mud system. The mud outlet downstream of the U-tube should be designed to maintain a minimum vessel fluid level of approximately 3 1/2 ft in a 16 ft high separator.

Assuming a 9.8 ppg mud and total U-tube height of 10 ft the fluid seal would have a hydrostatic pressure equal to 5.096 psi. This points out the importance for providing a large diameter gas vent line with the fewest possible turns to minimise line frictional losses.

DC mud gas separators are designed to provide safe drilling procedures during horizontal, underbalanced, h2s, or high pressure drilling. Our gas buster captures and separates the mud/gas then safely vents free gas to the flare line to be burned off while returning mud to the mud pits.

Our Mud gas separators are intended to sustain safety for high pressure wells or when sour gas may be present. Our units are closed bottom skid mounted model designed around safety and precision. Uniquely designed baffles break up mud and gas which is then expelled by the gas vent line to the flare line.


DC Solid control manufacture numerous size specifications including ZYQ800, ZYQ1000 and are capable of producing vessels of all sizes. DC Gas Busters have a 12” inlet from flow line, 12” gas vent line to flow line, 12” return line, and 20” manhole. If necessary these lines can be modified with flanged concentric reducers to your desired piping size. The run of the gas vent line continues to ground level for safe and efficient hook up to the flare line piping.

DC’s Mud Gas Separator has a lot of advantages including reliable safety, better treatment effect, long service life, etc. DC use high quality steel materials manufacturing normal pressure prevent H2S Mud Gas Separator,can effectively prevent the harmful gas erosion, ensure the man- machine safety production.

The mud gas separators should be able to handle a high proportion of mud solids and may experience hydrate plugging as a result of gas expansion through the choke. Designs based on conventional process practice, involving a float controlled liquid dump valve and a control valve to regulate gas pressure are not suitable because of the accentuated risk of malfunction due to plugging and the consequent need to provide a relief valve which itself may plug. Mud gas separator designs should therefore be based only on a liquid seal system matched to an adequate gas vent.

Liquid Throughputs

The volumetric flow capacity of the system should be based on an adequate gravitational rate from the mud gas separator. A typical liquid capacity of 6 barrels per minute of 12 pounds per gallons drilling fluid of average viscosity is a guide for vertical mud gas separator.


Liquid seal design

The liquid seal ensures that separated gas vents safely without breaking through to the mud tanks. The seal may be in the form of an external U-tube or may be based on a dip tube extending into a tank, usually the trip tank. The liquid seal hydrostatic pressure must be monitored against the back pressure of the gas vent line in the mud gas separator. It may be integrated as part of an instrumentation control system for the whole system.

Anti-Siphon Line

If the liquid seal is based on a U-tube design, an independent vent pipe, preferably 6 inches nominal diameter or larger, should be fitted at the highest point of the pipe work to avoid siphon effects and as a back-up to dispose of gas carried through the U tube liquid seal. The secondary vent need not extend to the top of the derrick. It should never be tied onto the primary vent.

Relief lines

All surface gas handling systems should have a means of diverting the flow from the choke and kill manifold through overboard relief lines and isolating the mud gas separator. In a blow-out situation, this may be the last resort to allow evacuation of personnel from the drilling rig. The pressure rating of the piping and valves on overboard lines should not be less than the pressure rating of the buffer

Drilling fluid gas-liquid separator is the first stage professional equipment to treat the gas invade mud. It is mainly used to remove the big bubbles with the diameter of about ≥Φ3mm.Most of these bubbles are the expanded gas filled in the drilling fluid in annular of wellbore. It would cause well kick if mot to remove it timely.

Operation principle

Drilling fluid with gas invades goes into the separator at the import tangentially and drops to a series baffles along the inner wall. After collision to increasing the contact area, It flows downward and become to a turbulent state which makes gas separate from mud and the free gas passes through the top of tank and discharged from the gas export. The length of gas export pipe can be determined at site and be induced to the safe place. The drilling fluid without gas will flow into the circular tank.

mud gas separator

How to Installation

1. Generally, the separator is installed on the surface next to the 1# tank. The surface should be flat and stable.
The main body is lifted vertically to the surface by crane at the auriculars on the top of main body and then put down slowly. Three places on the top of the main body are pulled tightly by the steel string to assure the main body to be vertical to the surface.
2. After installation, Exhaust line the 2# channel 60-80mm distance of the mouth of a well.(The line is oneself, if needed to manufacturer provide, explain away to the speak for).Connecting the 3# import to the rotary prevention or throttle conduit and close the 4#waste export, open the 7#mud export and connect to 1# mud tank by the pipe.
3. When in moving, disassemble the pipe and loose the tightened string. Lift the top of the main body to make the auricular plane by crane. The ladder can be used as bracket in this situation.


Discharge the mud in the separator totally when in spare time and other are not needed.

Mud gas separator separates the gas which is from throttle manifold and process the gas cut drilling fluid, removing the gas, natural gas, hydrogen sulfide, co, co2 which are mix in drilling fluid, and recovery the degassing drilling fluid, then it is further processed by vacuum degasser, it is send back to drilling fluid circulating tank.

After occur overflow and close the well and complete well control calculate scheme, the throttle pipe is soaked mud have already connected well, mud gas separator has already connected well.

1. When using the mud gas separator in installed cleaning value and U pipeline discharge value must be closed.

2. Checking the discharge pipeline safety fixed rope or chain.

3. Open the throttle pipe value which is leading to mud gas separator.


After start the well control process, the mud returned from hohlraum through the throttle pipeline enter into drilling fluid mud gas separator. The separated gas by mud gas separator is discharged and the mud is discharged from separator is directly return to shale shaker.

1. During the working, continuous monitoring mud gas separator and detection the returned shale shake tank mud.

2. After well control successful, open the bop and closed the throttle pipe value which is connecting mud gas separator.

3. Opening the mud gas separator cleaning value and all rock debris are discharged to pollution pool.

4. If use the U pipe separator, open the U pipe discharging value and clean it with water. The all solid are discharged to pollution pool.

5. Cleaning, washing and checking all manifold, pipe line and value and according the requirement of soft shut well and hard shut well of drilling design rearrange the throttle pipe and the working condition of mud gas separator.

Mud gas separator is a safety equipment in drilling fluid circulating system, which installed in front of shale shakers. But, how to
calculate the flow is a problem. Following is the instruction of all details.

Peak Gas Flow Rate. the critical time for mud gas separator blow-through exists when peak gas flow rates are experienced. Mud/gas separator
blow-through is defined as inefficient separator operation resulting in a mud/gas mixture returning to the mud tanks through the mud
return line.


Two situations can cause separator blow-through.

1. Friction pressure of the gas venting through the vent line exceeds the mud-leg hydrostatic pressure, resulting in evacuation of
fluid from the separator. Friction pressure of the mud through the mud return line is considered negligible because of its short

2. Vessel ID is too small, causing insufficient retention time for the gas to separate efficiently from the mud. This situation is
commonly called insufficient separator cut.

To estimate a peak gas flow rate properly, we must consider a “typical” kick. The typical kick will depend on the well location,
depth, type size, and component ratios of influx. Kick data should be based on previous offset well data and should be a realistic
worst-case gas kick. The well and kick data in Fig. 5 will be used in this paper.

The volume and pressure of the gas upstream of the choke must first be calculated.

The mud gas separator is designed to remove gas from the mud/fluid before it is transferred to the shale shaker system. It separates gas out of the mud after the gas comes out of hole.

The mud gas separator is strictly used for well control only. There are some events that this equipment is utilized in a well testing operation. Additionally, inspection for the gas buster must be performed frequently the same as other well control equipment.

mud gas separator

People tends to forgot about this since it is just only a vertical separator tank without high pressure specification like BOP, choke manifold, valves, etc. Erosion is one of the worst enemies to the vessel like this and it can be seen at the points where the drilling mud impinges on the internal wall vessel.

Each mud gas separator has limitation on much it can safely handle volume of gas. If the volume of gas exceeds the maximum limit, gas can blow through into the rig. It is very important that you must estimate gas flow rate on surface based on pit gain and kill rate in order to see how much expected gas on surface.

This will be the limitation on how much you can circulate for well killing operation. You can estimate the volume gas on surface by using well control kill sheet provided by several companies. You need to ensure that the vent line should be as straight as possible with a larger ID in order to minimize back pressure while venting the gas out.