The Study Of Constraint Mechanisms Of Seismic Information On Numecial Simulation For Special Reservoirs

The three-dimensional dynamic simulation of the reservoir is the key aspect of reservoir numerical simulation.But how to improve the prediction accuracy of the numerical simulation is always a problem for the traditional reservoir numerical simulation.With the development of 3D seismic technology,the application of seismic technology to depict the distribution of remaining oil in the late stage of oilfield development has drawn much attention.The aim of this paper is to explore the method of how to apply seismic information into the numerical simulation for special oil and gas reservoirs through geologic analysis,reservoir engineering methods,geophysical analysis on the basis of the theories of petroleum geology,reservoir engineering,reservoir physics,oil production engineering,geophysics,logging,mathematics and computer technology.Additionally,the numerical simulation of heavy oil-bearing reservoir in Shu1 area and volcanic reservoir in Bin3 area located in the eastern of China are carried out.For the heavy oil-bearing reservoir,the seismic and reservoir engineering data were analyzed based on three-dimensional geological modeling,the reservoir numerical simulation with seismic information was conducted,the dynamic changes of SAGD steam chamber was simulated,the distribution of remaining oil after recovering by steam stimulation converting to SAGD was analyzed,and finally related measures were put forward.For the volcanic reservoir,the seismic and reservoir engineering data were analyzed based on three-dimensional geological modeling,reservoir numerical simulation with seismic information and streamline flow simulation were conducted,the remaining oil distribution was analyzed,and finally some measures were put forward,which were helpful to the high and stable production in the oil-field.The constraint mechanisms of seismic data on reservoir numerical simulation are analyzed by seismic forward modeling on the basis of petrophysical model.The changes of reservoir parameters such as fluid,pore pressure and reservoir temperature will lead to the changes of seismic attributes according to the correlations between reservoir properties and seismic response characteristics.Based on the seismic petrophysical theory,there is a certain correlation between the seismic attributes and physical properties of reservoirs.The static and dynamic data of the reservoir model can be converted to elasticity and acoustic parameters,based on which the synthetic seismic profiles can be founded,which are used to compare with the measured seismic data.Due to the uncertainties of the reservoir models,there is a difference between the synthetic seismic profiles and the measured seismic data.It is necessary to continuously adjust the parameters of the designed reservoir models until the synthetic seismic response profiles are similar to the real seismic profiles.The reservoir model obtained from the seismic constraints is considered to be a real reservoir model,so it can improve the prediction accuracy of reservoir numerical simulation.Based on the above analysis,the process of reservoir numerical simulation is established,and the key technologies are illustrated.The reservoir numerical simulation method under the constraint of seismic information is different from the conventional method.Firstly,establishing three-dimensional geological model and determining the appropriate physical model,secondly,analyzing the correlations between the seismic attributes and the reservoir model parameters and conducting the post-stack seismic forward modeling,finally,carrying out the historical fitting and seismic fitting.Based on the reservoir model obtained by the above process,the distribution of remaining oil can be described.The key step of the above process is how to synchronize the historical fitting and seismic fitting,that is,how to deduce the reservoir evolutional history by the historical fitting using the seismic data and production data.The numerical simulation of steam chamber development in SAGD process for Shu1 heavy oil-bearing reservoir and the change of steam chamber shape in 3D in SAGD process were studied by the method of numerical simulation with time-lapse seismic.Shu1 heavy oil-bearing reservoir is located in the middle of the west slop zone of the west sag of Liaohe Basin.The development zone of steam chamber expands continually with the thermal recovery for several years,and the top of steam chamber is gradually closer to the top reservoir,which may melt bitumen there and lead to a passive situation for reservoir recovery.Therefore,how to simulate the dynamic change of the shape of steam chamber in 3D is a focus and the numerical simulation of steam chamber development in SAGD process is carried out by using numerical reservoir simulation method under the control of time-lapse seismic.The changes of temperature,fluid replacement and reservoir property in thermal recovery of reservoir can lead to the changes of seismic response.The seismic attributes related to the development of steam chamber are picked out based on time-lapse seismic data in two different periods.Based to the comprehensive analysis of time-lapse seismic and reservoir engineering material,it is found that the seismic amplitude attribute is the most appropriate one.Production fitting and seismic fitting are conducted simultaneously using conventional production data and time-lapse seismic data.Under the premise of ensuring the accuracy of well-fitting using production data,the model parameters and position are determined and inter-well uncertainty is reduced by using inter-well dynamic information provided by time-lapse seismic data.Our work can not only shorten the historical fitting period effectively,but also simulate the shape changes of steam chamber in SAGD process in 3D space.The the simulation results are verified by temperature data and actual production data of wells.The results of steam chamber numerical simulation in SAGD process in Shu1 area can guide the making of reservoir recovery program.According to the numerical simulation result of remaining oil distribution and steam chamber distribution in 3D space,and the production dynamic data,the well pattern is improved and the working system is optimized in the remaining oil enrichment area.Additionally,a comprehensive adjustment program including fill hole,recovery steam injection well,increase liquid production rate,optimize steam injection volume and injection/production ratio is made.The reservoir numerical simulation results indicate that the recommended program can increase oil production by 7×104m3 and enhance oil recovery by 2% after 8 years.And after 13 years,the oil incensement reaches up to 27 × 104m3 and the enhanced oil recovery is 9%.The volcanic reservoirs in the western part of the Bin3 area are located in the northern margin of the Dongying depression in the Jiyang Depression.The tectonic fault system is complex and the fracture development is unclear.The dynamic analysis shows that the typical production of fractured reservoirs in the mining process,that is,once the water break,the water content increases rapidly,oil production is decreasing rapidly.However,due to the earlier production of reservoirs,lack of cracks and logging data,it is difficult to quantitatively describe reservoirs and crack modeling.The accuracy of reservoir numerical simulation is low,which leads to unclear understanding of reservoir mining rules,unclear direction of plan deployment problem.In view of the above problems,the numerical simulation of reservoirs with seismic attribute constraints is carried out.The relationship between seismic attribute and reservoir model parameters shows that the eigenvalue correlation property is closely related to the distribution of volcanic reservoir and the degree of fracture development.Based on the method of reservoir numerical simulation with the constraint of seismic attributes,the distribution of fracture in three dimensions is revealed after the numerical simulation work in volcanic reservoir in the west of Bin3 area.This volcanic reservoir,located in northern margin of Dongying sag in Jiyang depression,has complex tectonic fault system and unclear fractures system.the dynamic data shows a typical fractured reservoir,which means the water content rises and the oil output drops rapidly as soon as the breakthrough of water content.Because of the absence of fracture log data,quantified description and fracture modeling of the reservoir is difficult and the accuracy of the numerical simulation is relatively low,which results in series of problems such as the unclear law of reservoir development,undefined adjustment direction of develop plan and so on.Here,reservoir numerical simulation with constraint of seismic attributes was carried out.The relationship between seismic attributes and parameters of reservoir model shows the eigenvalue coherence attributes have the closest relation with the distribution of volcanic reservoir and the development degree of the fractures.With the comprehensive analysis of volcanic rocks characteristics,log dara,core data and production data,it is discovered that the tight basalts with dense fractures is usually developed in the area of eigenvalue coherence attributes with high value,while the fractures is sparsely developed in the area of eigenvalue coherence attributes with low value.The relationship between seismic inversion attributes and parameters of reservoir model shows the tighter lithology corresponds to higher wave impedance and denser fractures.The Anisotropy of wave impedance attribute in three dimensions is corresponding with the anisotropy of physical properties of volcanic rocks.Because of the great anisotropy in volcanic reservoir,the accuracy of geological model is relatively low,and it is difficult to describe the distribution of the fractures precisely.Therefore,seismic attributes are applied into the numerical simulation of volcanic reservoir.The distribution of fractures and rules of reservoir development can be known through the seismic information and dynamic data.The predominant direction of the fracture zones is discovered by tracing the migration path of oil,gas and water which is along the descending direction of pressure gradient using the method of streamline simulation with constraint of seismic information.Not only the distribution rules of fracture zone in three dimensions are cleared,but also the history matching is improved,and the accuracy of reservoir numerical simulation is improved.The numerical simulation results of the volcanic reservoirs in the western part of the Bin3 area effectively guide the adjusting plan of reservoir exploitation and drilling trajectory design.The results of the numerical simulation constraint with seismic attributes show the abundance of remaining reserves are high in the 674-21 well area,the Bin 674-19 well area and the western part of 674-3 wells,which are the most potential area.Through the research of remaining oil development by horizontal well,injecting water complements energy and steam stimulation,it is suggested that the remaining oil should be developed with horizontal well,the fracture-developed zones should be avoided in drilling the horizontal wells.At the same time,well pattern should be infilled reasonably with the consideration of the well pattern arrangement,and it should give priority to the middle and top area of the reservoir to avoid the edge water.According to the above principles,new wells location is proposed,and the horizontal well trajectory is designed.The results of this study have been practiced and verified in the oil field.At present,the production of horizontal well B674-P1 reach up to 17 t per day at the early of production,which is 8-10 times to the average production of those old wells in this block.Our work can make great contribution to the improve oil production in the Bin3 area.