Mantashev funded the Baku-Batumi pipeline which was launched in 1907, becoming the world's longest pipeline, 835 kilometers long. From 1899 to 1909, his company by volume of fixed capital (22 million rubles) was the largest in Russian industry. It is said that before buying oil wells Mantashev personally examined them. He knew that a rich deposit may suddenly dry up, and vice versa: a well seemingly lacking in prospects could end up as a rich fountain. Surrounded by a group of geologists and petroleum engineers, he visited the sites asking countless questions, carefully studying land-color, softness etc.; he even smelled the land. Mantashev always inquired into the status of the neighbouring sites, often seemingly choosing them at random and saying : "It's here, start digging." No one could understand what it was that made him choose that particular spot. But his decision was always final. The great paradox was that when drilling commenced, an oil fountain was almost always discovered.