These hydrocarbon deposits, collected in porous rocks trapped beneath impermeable cap rocks, comprise commercial oil fields.
ðiːz hˈaɪdɹəkˌɑːɹbən dᵻpˈɑːzɪts, kəlˈɛktᵻd ɪn pˈoːɹəs ɹˈɑːks tɹˈæpt bᵻnˌiːθ ɪmpˈɜːməbəl kˈæp ɹˈɑːks, kəmpɹˈaɪz kəmˈɜːʃəl ˈɔɪl fˈiːldz.