The physical properties of reservoirs determine the ability on accumulating hydrocarbon. As one of the unconventional hydrocarbon reservoirs, the volcanics own the different characteristics from the clastic rocks on physical properties. The study on the relationship between physical and electrical properties of deep volcanic reservoirs was conducted, using the Luxi area of Junggar basin as an example. By our study, some conclusions have been made: The heterogeneity of physical properties is strong in volcanic rocks whose porosity and permeability vary in different lithology and lithofacies; different rocks in a same well have various values of porosity and permeability, and a certain type of volcanic rock has different values of porosity and permeability in diverse wells. According to measured data, the value of porosity an permeability in erupting and effusive facies area are high, while in volcanic channel and extrusive facies as well as volcanic sedimentation facies are low. Unlike the clastic rocks, in volcanic rocks there is little relationship between porosity and permeability and all of them do not have close relationship to the buried depth. Different electrical responses have different relationship with the porosity of one certain lithology, while one certain electrical property has different responses for the porosities of different lithologies; comparatively speaking, the porosities of tuffites, breccia correlate intensively with GR, SP and AC, so these electrical parameters can be utilized to predict the physical properties. This study illustrated that the relativities between porosity and GR, AC, and SP are Por=-0.6189×GR+52.691 (R2=0.9311), Por =-0.3771×AC + 34.5 (R2=0.8876) and Por = 2.1458×SP + 79.404 (R2=0.8236).
Characteristics, controls and geological models of hydrocarbon accumulation in the Carboniferous volcanic reservoirs of the Chunfeng Oilfield, Junggar Basin, northwestern China
