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Fractured Hydrocarbon Reservoirs Pre-stack Seismic Detection Methods And Techniques

Posted on:2013-06-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:J Y LiuFull Text:PDF
GTID:1220330377450416Subject:Earth Exploration and Information Technology
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Fractures within the earth’s crust are distributed everywhere, they areconstructured within the long perod of tectonic movements and other geologicalforces, fractured reservoir beds on earth are widely developed. Now, the oil and gasproduction of fractured hydrocarbon reservoirs accounted for more than half of theworld oil and gas production. Fractured reservoirs in the country have beendiscovered in recent years more and more, such as the Ordovician fractured carbonateoil and gas reservoirs, fractured shale oil and gas reservoirs of the Qaidam Basin,Dagang Oilfield (Chenghai) Ordovician carbonate fractured reservoir, tight sandstonecracks in oil and gas reservoirs in Sichuan, Xinjiang oilfield of forest fires, spitKazakh hills, Shanshan Oilfield, Changqing Ansai oilfield victory Bonan oil field,Daqing oilfield in Jilin legislation, dry safety, Xinmin oil field, almost every major oilregion has fractured reservoirs throughout the country. Obviously, the exploration offractured reservoirs is increasingly becoming an important oil-gas exploration strategyto take over the outproduced area. Especially in the today of the high degree ofexploration, most of the basin’s large or relatively simple anticline oil and gasreservoir has been exploration and exhausted, fractured and non-structural explorationof oil and gas reservoirs has gradually become one of main exploration direction ofevery major oil field in China, the key point is how to solve the prediction problem ofthat kinds of lithologic reservoirs.At present, there are two categories of seismic fracture detectiontechnology,which use the different kind of seismic data individually.The one is thepost-stack prediction technique, the other is the pre-stack prediction technique. Thepost-satck technology commonly used are those of large-scale coherent analysis of thetechnology, image processing, curvature analysis techniques, the inclination detection techniques, stress analysis techniques, they usually use post-stack seismic data asbasical input data, their study object is the large-scale faults of entire fracture system,the predicted effect indicates the skeleton and outline of mesh-shape fracture system,which is showed as a linear distribution on the result plane map and their number isless.For a larger number of small or micro-fracture system, post-stack fractureprediction technology is powerless to do anything.Reason why the post-stack fracture prediction technique is failure, thefundamental reason lies in the post-stack seismic data has less amount of seismicinformation, i.e.,it is lack of offset information and azimuth information, so that youlose the theoretical basis and foundation of the anisotropy to detect micro-fracture.In order to overcome these shortcomings, we can take advantage of characterswhich pre-stack seismic data has a large amount of data and information to predict theentire fracture system by detecting the seismic response which is contained withinprestack seismic data that can be described by aimuth-offset two dimensionalspace-time domain. To this end, we developed a3D prestack fracture predictiontechnology based on conventional P-wave prestack seismic reflection amplitude, i.e.,itis done following: the extraction of the P-wave prestack azimuth amplitude,thenellipse fitting for fracture prediction. The methods and techniques used in oil fieldactual work area has obtain a better practical application effects. I achieved someconclusions following as:(1) The study of methods and techniques.Through the basic theory study of theorientation characteristics of seismic wave propagation,I haved studied the basicprinciples of the corresponding the prestack crack prediction, and thus developed aspecific method and manner of prestack fracture prediction. I have laid a goodtheoretical and methodological basis for the subsequent programming.(2) Software development.Under the guidance of the principle of these methods,I have designed software architecture and supporting software, and developed themain software modules.I have developed prestack crack prediction software modulewhich has independent intellectual property rights.(3) I have a invention of prestack fracture prediction new technology, which hasapplied for national invention patent, the invention name is the fracture predictionmethods and devices, patent number is ZL201010205983.4.The main content of the invention are: to obtain the stacked CMP NMO gathersseismic data and related parameters for predicting fractures; to generate thecorresponding index data for prestack NMO-CMP gathers seismic data, and to obtain layer data by interpretaion of post-stack seismic data; to generate conventionalwide-azimuth prestack CMP gathers from conventional narrow-azimuth prestackCMP gathers; to obtain header information of prestack CMP gathers; to calculate theazimuth angle of each seismic trace; to obtain each seismic reflection amplitude of thetarget layer within pick time window; to take ellipse fitting by obtained the azimuthand reflection amplitude, and then to determine fracture orientation and fracturedensity. Embodiment of the present invention can improve the prediction accuracy ofthe fractured reservoir; and this is used to not only three-dimensional prediction offractured reservoirs, but also two-dimensional prediction,.It can improve the successrate for exploratory wells and drilling.(4) The actual data research.I have developed a set of work thoughts andworkflow of prestack crack prediction for fractured carbonate reservoir exploration. Itis used to practical application and has made a better effect.In practical applications, I select the Dagang CHENGDAO Sea as a researchwork area, carried out the research work of of Chenghai Ordovician weathering crustreservoir seismic prestack quantitative prediction of the actual production projects, themethods and techniques of this thesis are used in the production, and the researchresults reveal the cracks plane distribution law of the weathering crust of carbonateformation, and strong support for the deployment of the exploration wells.
Keywords/Search Tags:Fracture prediction, Orientation characteristics, Carbonate, Reservoirprediction
PDF Full Text Request
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