Abstract: On the basis of drilling cores,thin sections,imaging logging and 3D seismic data,the study discusses the effects of tectonic movement on diagenesis,fractures development and hydrothermal fluid activities of carbonate reservoirs in Y oilfield of the northeastern Zagros Foreland Basin.Tectonic movements from the late Cretaceous to the Holocene have most significant effect on the Cretaceous carbonate reservoirs in Y oilfield.During this period,because of compressional uplift,target strata were heavily eroded and weathered,which leads to development of an unconformity surface.Reservoirs below the surface suffered from severe dissolution.With the collision between Arabian plate and the Eurasian plate,and resultant folding and thrusting induced formation of fractures within reservoirs.Density and location of fractures were influenced by the intensity of folding and faulting,but also related to lithology.Fractures were mainly developed in the area around faults,and along fold axis or the lower end of fold limbs.In terms of lithology,fracture density in dolomite is obviously higher than that in limestone.Tectonic movements also controlled the hydrothermal fluid activities in Y oilfield.The faults are the main pathways of hydrothermal fluid into Y oilfield.Hydrothermal dolomitization occurred in grabens close to faults or fracture zones.Discussing the influence of tectonic movements on carbonate reservoir is beneficial for predicting and locating high-quality reservoirs in the study area,and optimizing production deployment of the oilfield.

Key words: tectonic movement, dissolution, fracture, hydrothermal dolomitization, Cretaceous, Zagros Foreland Basin