Tectonics of the Wysoka Kamieńska Graben (NW Poland) and implications for fault sealing potential

Abstract

Res er voir con fine ment by faults is im por tant for safe stor age of liq uid waste or hy dro car bons. Hav ing ac cess to 3D seis mic and bore hole data, we have in ter preted the tec tonic set ting of the Wysoka Kamieñska Graben (WKG) in the NW part of the Pol ish Ba sin and sub se quently made an in ter pre ta tion of the seal ing po ten tial of the graben-bound ing faults. The for ma tion and de vel op ment of the graben in the Late Tri as sic and Early Ju ras sic was con trolled by me chan i cal de coup ling in the salts of the Zechstein Group. The pri mary tec tonic fac tor trig ger ing the graben or i gin was dextral strike-slip move ment along the re gional fault zone in the Pa leo zoic base ment, transtensional ac com mo da tion of which in the Zechstein-Me so zoic cover led to de vel op ment of a horse-tail pat tern of grabens. Dur ing the Late Cre ta ceous, the graben un der went mi nor tec tonic in version. Seal ing po ten tial anal y sis of the graben-bound ing faults was per formed for the Triassic-Jurassic se quence in clud ing jux ta po si tion seal and fault gouge seal com po nents. Fi nally, we have fo cussed our in ter pre ta tion on the Ju ras sic se quence where the best res er voirs have been rec og nized. Our re sults in di cate good to mod er ate seal ing po ten tial of the Hettangian res er voir, poor to mod er ate seal ing of the Pliensbachian res er voir and lack of seal ing of the Bajocian res er voir. Hence, the Hettangian res er voir, char ac ter ized by large thick ness, low clay con tent and a large re gional ex tent, acts as a po ten tial storage for ma tion, be ing con fined by the graben-bound ing faults of the WKG. Key words: tectonic graben, salt de coup ling level, un der ground stor age, fault seal po ten tial, geo log i cal mod el ling.