CRANE, Texas (AP) — There are about 2 million abandoned oil and gas wells nationwide that haven’t been properly plugged with cement. Many of the wells are releasing methane, which is a greenhouse gas containing about 86 times the climate-warming power of carbon dioxide over two decades. Some are leaking chemicals such as benzene, which is a known carcinogen, into fields and groundwater. Regulators don’t know where hundreds of thousands of the abandoned wells are. That’s because many were drilled before modern regulations and record-keeping systems were established. In recent years, abandoned wells have been found under brush deep in forests and beneath driveways in suburbia.