Abstract
This paper provides a phenomenological description of a positive correlation between earthquakes and improvement of asphaltene problems during oil production in a Japanese oil field. The studied oil field is Field ‘M’, located in the central region of Japan. Oil has been produced from this Pliocene turbidite-sandstone reservoir since 2003. Serious formation damage occurred shortly after the oil on-stream, and the damage reduced the production rates of two wells. Based on the asphaltene sludge collected at the surface production facility and other supporting facts, the damage was identified as caused by asphaltene in the reservoir.
Severe asphaltene problems similar to those observed in other cases (Leontartis and Mansoori 1987; Garcia et al. 2001; Kokal et al. 2003; Strippoli et al. 2010; Al-Qattan et al. 2012) have been reported in Field ‘M’. The oil production rates of the reservoir responded positively to certain earthquakes that frequently hit this field. Based on a phenomenological analysis of the relationships between the earthquakes and the production behaviors of the field, we concluded that the following three criteria must be simultaneously satisfied for an earthquake to influence and improve the productivity of the wells in Field ‘M’: (1) The productivity of the well is lowered, due to severe asphaltene problems in the reservoir with a flowing wellhead pressure of less than 690 kPa·abs (100 psia); the corresponding pressure loss created by asphaltene deposits in the near-well reservoir region is approximately 6,895 kPa to 10,343kPa (1,000 psi to 1,500psi). (2) The well is producing oil from the reservoir. (3) Earthquakes with a seismic intensity of not less than 3 hit the field.