Study On Reservoir Characteristics And Seepage Mechanism In Ying Dong Structure

For sandstone reservoirs, the study microscopic pore structure and flow rule is still the key areas of research at home and abroad. Study and master the understanding of reservoir properties are the basis of reservoirs, reservoir evaluation, protection and rehabilitation, for oil field exploration and development work to improve the oil recovery has very important significance. Microscopic pore structure characteristics analysis of reservoir water distribution can understand the state in the formation; Study of reservoir damage mechanism to facilitate the protection of reservoirs in oil exploration development process; The research of water displacement efficiency, fluid flow rule, microscopic residual oil distribution characteristics can better understand the characteristics and microscopic distribution of water seepage in the formation,there has very important significance for water drive reservoir and the remaining oil.In this paper, a large number of laboratory experiments had been carried on Ying Tung oil drilling core rock samples. Using a combination of macro and micro point, combined with surface geology, testing and logging, combined with general tools and advanced methods, combining the research and production of indoor practice which I call it" a combination of Five" principle, The microscopic characteristics and percolation mechanism of the reservoir to conduct a comprehensive study and evaluation. Combined with the methods of conventional mercury capillary pressure curve analysis, constant pressure mercury capillary pressure curve analysis, nuclear magnetic resonance analysis, cast sheet pore characteristics image analysis, what deeply reveals features of the area revealed the microscopic pore structure of the reservoir rock; Through comparison of wettability of the new core rock and sealed coring results wettability of the rock sample analysis and comparison of experimental results, getting a understanding of the block reservoir rock wettability characteristics; based on the understanding the mechanism of low permeability rock flow, combine with low permeability reservoir rock flow characteristics, we had a deep understanding of the Seepage law of low permeability rocks that block; on the basis of the analysis of Sensitivity minerals of reservoir rock and the potential damage to pore structure of rocks to the reservoir, study the sensitivity of the flow rate, water sensitivity, salt sensitivity, alkali-sensitive, acid sensitivity of reservoir rocks, Recognizing the sensitivity of various degree of damage, pointed out the exploitation of oil fields to prevent damage to sensitive method; Recognizing the sensitivity of various degree of damage, and pointed out the exploitation of oil fields to prevent damage to sensitive method; Use of reservoir rock, simulate actual reservoir conditions, using different diameters reservoir core rock samples experimental analysis of water flooding efficiency factors and their variations, eventually through observation experiments of microscopic flow, to analysis microscopic seepage law of reservoir and Occurrence of residual oil, providing next exploration for study of geological exploration reserves the research and development program to provide basic information and data preparation for the area, and to provide a basis and recommendations for the oilfield to improve the development effectiveness and recovery.The experimental study of Rock samples in the area showed that:reservoir potential damage to the mining process in Ting Tung oil, including:When the reservoir pressure and temperature decrease of the fluid into the reservoir or the water is not compatible with the formation, the resulting formation damage caused by inorganic precipitation, such as CaCO3, MgC03, Ca (OH)2and so on; Bottom formation temperature drop will cause the wax, resin and asphaltene organic precipitation,then cause formation damage; Various sensitivity damage and water damage sensitive> speed-sensitive damage> alkali-sensitive damage> acid sensitivity damage. Wettability experimental studies have shown that, Ying Tung oil reservoir rocks are mainly hydrophilic, part of the rock has a weak hydrophilic or neutral wetting characteristics. Low permeability rock flow characteristics experimental results show, When the Ting Dong oilfield formation water through low permeability rock seepage, obey Darcy flow, there is no pressure gradient; When the formation of oil (viscosity6.0mPa·S) low permeability reservoir rock by a single-phase flow, When the permeability of the rock sample k<38.8×10-3μm2, the presence of both the pressure gradient, there is also a critical pressure gradient, and the starting pressure drop with increasing rock permeability.The water flooding experimental results show that:water flooding efficiency factors have displacement speed, micro-heterogeneity, gravity and macroscopic heterogeneity. There is an optimal oil displacement speed for waterflood efficiency; when large-diameter core samples of water flooding, As the flow field generated by a small rock sample of one-dimensional linear flow becomes part of a two-dimensional percolation, microscopic heterogeneity in the reservoir in the longitudinal direction and effect of gravity in water flooding, reduce its oil displacement efficiency. Microscopic model flooding photos and video analysis experiments show that:Oil- water two-phase flow with a strong micro-heterogeneity and micro obvious fingering phenomenon, presents a non-uniform advance; water flow presents "channel flow state" feature. The residual oil was mainly large oil "dead end" type of fork inside, followed by isolated and surrounded by water into droplets, residual oil edges at the corners, edges of the hole wall film presence. The water relative permeability Experimental studies show that, Ying Dong oil field oil-water two-phase flow area changes, irreducible water saturation is high, a large residual oil saturation change; the relative permeability curves reflect Ying Tung oil reservoir rock wettability is mainly hydrophilic; Reservoir water relative permeability curves can be seen, with increasing core water saturation, the oil permeability decreased faster, water permeability Increase slow and end little value, This shows that as the water rises, not only oil fell, mining liquid index will show a decline in state, Indicates the difficulty is large with improved fluid production to achieve oil fields stable production.