Abstract: Low-resistivity layer (reservoir)in Junggar basin features multi-origin, wide distribution and difficult identification. This paper discusses its origin and presents the identifying method. Study shows that low-resistivity layer is characterized by low resistivity, sand-mud interbedding, developed micropore and weak drill show, with montmorillonite and illite-smectite interstratified minerals. And additional conduction, high salinity, high irreducible water saturation and drilling mud invasion, etc. are the key factors for forming low-resistivity layer (reservoir). Well log and logging, etc. are the main identifying techniques for it.

Key words: Junggar basin, low-resistivity layer (reservoir), origin, identifying method