Shale Gas Desorption

Leutert product line of coalbed methane and shale gas desorption canisters allow the operator to determine the potential of the reservoir that is explored. A coal and shale gas desorption canister is used to hold a freshly drilled core sample. The desorption canister is sealed as soon as possible after the core is retrieved from the well. Inside the desorption canister desorbed gas is collected and the reservoirs gas content is determined in accordance with ASTM D 7569/D 7569M: “Standard Practice for Determination of Gas Content of Coal - Direct Desorption Method”. Shale gas content is one of the most important parameters for reserve calculation and sweet-spot prediction.
 
Leutert coal and shale gas desorption canisters are made of stainless steel. Stainless steel desorption canisters can be used for higher temperatures where PVC canisters have temperature limitations. No aluminum was chosen to avoid any chemical reaction between the desorption canister and the hydrocarbon, which can be enhanced by the presence of water as a solvent. Different diameters of desorption canisters are available to fit the core as tightly as possible to minimize headspace. The cylindrical body of the desorption canister is welded shut on one side. The welded cover has a pressure port that leads into a drain hose assembly terminating in a ball valve. Each drain hose assembly features a small pressure gauge for internal pressure readings. A temperature sensor is also integrated in the welded cover. It enables the internal canister temperatures to be recorded. An eye bolt allows the desorption canister to be lifted easily.
 
The second end of the cylinder is intentionally left open for loading core or cutting into the canister. The opening is closed with a silicone donut seal assembly. When squeezed, it seals the open end of the desorption canister. The position of the seal can be varied depending on the length of the core or the amount of cutting loaded into the desorption canister. This reduces internal void volume and avoids the need for Teflon spacers to reduce the headspace.
 
To speed up the desorption rate, the desorption canister temperature is increased to the second stage desorption at reservoir temperature. The Leutert Dry Heating System can hold up to three desorption canisters. Each compartments temperature of the dry heating system is controlled individually. The Dry Heating System is light an can easily be transported to remote locations.
 
The amount of gas desorbed is measured using a Volumetric Displacement Apparatus. The Volumetric Displacement Apparatus is equipped with three glass burettes of different volumes. The desorbed gas is fed from the desorption canister into the water filled burettes. The water is displaced by desorbed gas and the volume can be read directly from the graduation printed to the burettes. The different sizes allow more precise readings. The smaller the burette, the finer the graduation and the better the resolution.
 
All measured data may be entered into the Leutert Direct Desorption Spreadsheet. The Direct Desorption Spreadsheet is used to estimate the lost gas value and to calculate the total gas desorption from a desorption canister test. The spreadsheet corrects the measured gas volumes to standard pressure and temperature conditions and then plots this data to estimate lost gas.

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