Seismic survey lines are the likely origin. Additionally, mineral exploration also involves "gridding" for drilling purposes. Bulldozers are used to clear gridlines in rectangular patterns so drilling rigs can gain access to precise points on the grid. The drill results are then correlated with drilling depth and geographical position to outline ore bodies in 3D.
Natural gas pipelines are commonly run through isolated regions, and they have access easements/roads each side of the pipeline.
Even if the pipeline is buried (as many are), the access easement will still be visible from the air.
China has the worlds longest NG pipeline - it's 8700kms long and runs from Turkmenistan to Southern China.
There are 8 branches from this pipeline planned, with 3 already installed.
This pipeline brings China's pipeline total, to over 40,000 kms of NG pipelines.
World's longest natural gas pipeline operationalised: China - The Hindu