Chapter 7. Alternative North Sea Jurassic sequence stratigraphic schemes

Abstract The chapter reviews over 40 previously published North Sea Jurassic sequence stratigraphy schemes. Some of these works have applied the originally published J sequence schemes, while 18 have established new schemes. The most significant of these are discussed and compared to the newly defined J sequences. Most of these additional documented schemes have been defined for the Upper Jurassic interval, with a more limited number of schemes to the Lower and Middle Jurassic. Different authors have adopted a wide range of sequence notation methods and none of the publications defining the new sequence schemes has offered detailed sequence definitions. Due to the ensuing confusion, it is recommended that a more formal method of sequence definition is adopted as part of the stratigraphic code. In intervals in which reservoir successions are developed, such as the Fulmar Sandstone Member in the J56 to J63 sequences, particularly in fields in which extensive coring has taken place, authors have usually been able to recognise additional sequences, which are probably at fourth order scale, at a higher resolution than the defined third order J sequences.