Study On Wave Equation Simulation Of Seismic Characteristics For Carbonate Reef And Bank Strata

The carbonate reef and bank were perfect reservoir for oil and gas. Reservoir of reef and bank was regarded by geologists and geophysicists all the time.There were many kinds of trap in reef and bank.They had much a lot of advantages for oil and gas generation and accumulation.So study on organic reef and bank was an important content in oil and gas exploration.Both the definition structure classification development,sedimentary facies and sedimentary environment of carbonate reef and bank, and the reservoir characteristics,the characteristics of seismic reflection wave and well logging response,identification and prediction of reservoir,were strategical.But reef and bank strata was inhomogeneous,heterogeneous and differential,quantity of seismic sections was usually poor,so it's very difficult to identificate and forecast reef and bank reservoir.It's extraordinarily significant to study on this item.In this paper, research was executed in two aspects.On one hand,characteristics of geology,well logging and seismic wavefield response about carbonate reef and bank were analyzed systematically.On the other hand,seismic wavefield numerical simulation by wave equation in frequency-wavenumber domain was studied typically.Afterwards,two sectors were associated.All kinds of geological model on reef and bank strata were created,then seismic wavefield modeling and migration through wavefield continuation theory using wave equation were performed to these models,both prestack sections and poststack sections.The schemes of seismic response from reef and bank strata were established by this way.The characteristics of reef and bank strata could be used to oil and gas exploration in carbonate rock.Extensionally,there are three steps.Firstly the definition classification development,sedimentary facies and sedimentary environment of carbonate reef and bank were analyzed through much seismic data on reef and bank oilfield in the word,then the characteristics of seismic reflection wave and well logging response about reef and bank reservoir were generalized.The source of these characteristics is reef and bank strata's geophysical properties.Secondly,two dimension closed structure geological models were created on the base of control points.Then wavefield forward modeling and migration to these models were perfomed by wave equation continuation theory in frequency-wavenumber domain,including three methods which were phase shift,phase shift plus interpolation,splitting step Fourier.Effect and fitness to seismic wave velocity change horizontally were observed and compared among three methods.It's proven that the method of phase shift plus interpolation was best.So it was used in seismic wave field forward modeling and migration.Thirdly,algorithm of common shot gather's wave equation forward and migration based on Huygens' Principle was studied.Prestack seismic wavefield numerical simulation of reef and bank Reservoir was executed.Then the common shot gathers' wavefield characteristics were analyzed conscientiously.Effect of the algorithm was certificated.