Coalbed methane recovery when low pressure, low pressure conveying, in theory, the use of more economical nearest reasonable. In fact, due to the external input of coalbed methane if it has affected more mature pipeline network, whether the output to match market demand and other factors near the field, often in place is not the most economical use of external input solution. CBM external input to determine the best solution, need to be analyzed from the following two aspects: on the one hand, if there is gas surrounding gas pipelines have been built outside the transmission should take full account of the use of coal-bed methane gas areas surrounding the pipeline has been built to save pipeline construction investment; other hand, when the economy than when the external input solution election, due to lower coal bed methane wellhead pressure, using different booster program, which boost investment and operating costs are also different. Therefore, in the preferred booster program to deal with the whole process of the outer wellhead to lose overall comprehensive comparison.
Coalbed methane relative gas, gas composition is relatively simple, and does not contain an acidic medium, low wellhead pressure, so the production process is simpler than the natural ground, without purification, dehydration can only boost than lose. CBM surface gathering process should be used to set the low pressure gas, segmented booster, the total process centralized processing. In the process of CBM gathering ground, the booster gathering process is key to the process. Reasonable assurance level is crucial gathering system pressure system, not only can save the CBM ground construction investment, but also reduce operating costs. Determine coalbed methane flow, target market, the gathering, transmission outside pressure overall optimization. CBM wellhead pressure is very low, generally in the 0.2 ~ 0.5MPa, need to set the gas stations, treatment plants set compressor supercharging. According to CBM wellhead pressure, external input pressure, estimating gas gathering station outbound different pressures and gas gathering stations, treatment plants, investment, and then determine the optimal pressure coalbed gas gathering station and into the treatment plant, so that gas collection compressor stations and treatment plants to optimize the configuration so that pressurized to minimize the CBM investment.
Suitable for CBM surface gathering compressors are mainly two types of reciprocating and centrifugal. The main characteristics of a centrifugal compressor is large displacement, light weight, simple structure, smooth flow, the disadvantage is prone to surge, single-stage compression is relatively low. The main features of a reciprocating compressor is a high efficiency, high compression ratio, stability requires a lower intake pressure, no surge phenomenon, the disadvantage is that the complex structure, the flow is not balanced. Due to the smaller coal-bed methane gas, flow fluctuations, and the compression is relatively high, it is difficult to meet the requirements of centrifugal compressors. Due to the relatively high pressure reciprocating compressors, flow adjustment range is large, more suitable for flow and pressure changes, so use a reciprocating compressor is more appropriate.
