Assessing Methane Emissions from Shale Gas Production in China: A Two-Tiered Mobile Measurement Approach.

Area of Science:

• Environmental Science
• Energy Science
• Atmospheric Chemistry

Background:

• China possesses the world's largest shale gas reserves but lacks detailed methane emission data.
• Rapid expansion of shale gas production necessitates accurate emission assessments.

Purpose of the Study:

• To quantify methane emissions from China's major shale gas production blocks.
• To identify primary sources of methane super-emissions in upstream production.

Main Methods:

• A two-tiered mobile measurement approach was employed, combining mobile laboratories and stationary downwind monitoring.
• Measurements covered 125 well pads across four key production blocks, representing 84% of national output.

Main Results:

• Methane emission rates varied significantly, from 0.002 to 98.86 kg/h.
• A small fraction of well pads (10%) accounted for a large majority (89%) of emissions.
• Estimated total methane emissions for 2023 were 16,842 tons, with a leakage rate of 0.10%.

Conclusions:

• China's shale gas methane leakage rate is comparable to U.S. dry gas fields.
• Gas lift venting, compressor incomplete combustion, and process venting are key super-emission sources.
• The mobile measurement methodology provides a robust basis for regulatory policy development.