Experimental Study On The Reservoir Character And Seepage Law Of Ultra-low Permeability Glutenite Reservoirs Of Huabei Oil Field

Combining with the experiments of rate-controlled mercury penetration, nuclear magnetic resonance(NMR) and physical simulation, the paper compared analyses the micro pore structure and the content of moveable fluid of the different ultra-low permeability glutenite reservoirs of Huabei Uliastai oil field. Then, based on the above research, the seepage law of the singe phase fluid and two phase fluids were studied. The research results are as following:1.The average of throat radius and permeability of the ultra-low permeability glutenite reservoirs have a fine power function relationship. Throat radius is the main factor of controlling the permeability of reservoirs. Small throat radius, high heteroge-neous degree and higher content of clay are the main factors of strong reservoir sensitivity of the ultra-low permeability glutenite reservoirs.2.NMR testing results show, for the ultra-low permeability glutenite reservoirs, T2 relaxation pectrum have more mono peaks than sandstone. The maximum value of T2 relaxation time lies between sandstone and conglomerate. The value of cutoff T2 is larger than general ultra-low permeability sandstone reservoirs. Parameters of moveable fluid become lager as permeability increases, and their relation gets better as permeability increases. Heterogeneous degree is stronger as permeability decreases.3.From the experiments of starting pressure gradient testing, for the same rock sample, starting pressure gradient of oil phase is larger than that of water phase. With permeability increasing, starting pressure gradient of oil and water phase decrease, and the decreasing degree becomes weak.4. Considering oil and water viscosity and effective permeability, the maximum of oil and water mobility were calculated in the relative permeability testing. By the maximum, oil and water flowability of the different ultra-low permeability glutenite reservoirs were compared.5. Combining NMR with physical simulation of low permeability reservoir, a new method of testing relative permeability curve was put forward. The new method adjusts irreducible water saturation and residual oil saturation, improves experimental precision, and makes the relation between permeability and oil displacement efficiency gets better. For the differently relative permeability curve, there are evident relationship between T2 geometric mean value and movable fluid percentage, movable oil saturation, imbibitions efficiency, expulsion efficiency, total oil displacement efficiency.6. Based on the reservoir characters of ultra-low permeability glutenite reservoirs in this paper, combining with previous evaluation standard suiting with the low permeability reservoirs, a comprehensive evaluation has been taken on the ultra-low permeability glutenite reservoirs of Huabei oil field.