Supplimentary System for the Study on Seismic一Stratigraphic Sequences of Sedimentary Basin一I

A Seismic一Sequence Stratigraphy Supplementary System of Sedimentary Basins (abbreviated as 4S)was established by the author based on studies of the basins such as Caidam, Jungar, Erdos, North China and Nanning. 4S, which wnsisting of three main blocks, data of exploration statistics, establishment of quantificational method and the opening of the model, is a microsoft system mnsistuated of more than 4000 sorce statements, its functions include the synthetical data一。peration of ground geology, seismology, well logging and sample analysis quantitative study many of the problems realated to seismic一sequence stratigraphy of the target stratum such as the sedimentary facies, sedimentary system,flow direction of palaeodrainage, prospect the distribution of source,reservoir and cap rocks of hydrocarbon generation, seis.mic simulation of the model of two一dimentional sedimentary model, three一dimentional slice of sedimentary sequence and its surficial morphologic image and so on. Both of the data systems used in 4S and the target result are different from the currently adopted ones that used especially for the explaination of seismic data and basin modelling. There are five spectattttes of 4S: (1) lnverstnea aata. 1t mcmaes an of the aata ana stattsttcs of surncial geology, well logging, seismic exploration,, sample analysis, downhole oil一gas determination, and digitized concepts and experiences.(2)Quantitatited analysis. All of the descriptive information are digitized, this led to the quantitative analysis of lithology, sedimentary environment, sedimentary system and so on. (3) Pat- terned explaination. Set up a model on the basis of。known spot firstly, then use it in the frontier area. (4) Software一equipped system, i. e.,block programme structure,it can data out more than 40000 statements, over 40 figures and 20 more tables. (5) Automatized programme. There are 3 blocks, 8 grades of menu and more than 180 sub一routines that can run as a whole programs or seperately,moreover, the oprator can joint the sub一routines as he will. 4S data, figures and knowledge bank are sub一divided into four sub一reservoirs, they are:original data source,intermediate data, figure and knowledge material. Original data includes the message of outcrups, section of drilling hole, seismic exploitation, sample teat, and downwell oil一gas determination Intermediate data is composed of the data generated during the running of system; Figure sub一bank consists of the source figure and final figures,Knowledge sub一bank is the foudation of general concepts and some special concepts, such as sedimentary facies and standard models. There are eight explainning models of 4S that established based on the konwn part of a basin, they are: (1) Time一lithologic sequence Markov chain model. Use the quantificated method of Markov chain to determine the known lithologic sequence,extract out the multi一models of lithofacies,and contrast them with standard models,then confirm the genetic type of the litho一seqquences. Generally, the results will be better if the lithologic assembledge profile is used to analysis the count matrix and transformation matrix of every lithostratigraphic unit. (2) Frenquence spcetrum analysis model of time一lithologic sequence. Marke spectrum analysis on the known sequences and identify the maximum cycle and wave band of a certain typical geological feature that found in a sequence. The maximum cycle and wave band should be similar if the sequences have correlated ge- netic type. That is to say, if a geological phenominon occured in two sequences isochronously and with simi- lar extent,then the sequences should be genetically correlation. (3) Various kind of poly一statistical model:4S can simulate data by means of funtional relations, it e- quipped with basically complete poly一statistical methods, and has the digit一opration such as digit wave filter, Fulier period analysis and correlation analysis. (4) Velocity一lithologic assembledge of sedimentary facies model. This model is the basis to explain of the underground facies. It is revealed that as the sedimentary sequences of terrigenous basins are thin polylithologic assembledges, so the seismic velocity, besides its normal relation with the burial depth and geological time,is mainly affected by the factors that are related to sedimentary condition such as lithologic assembledge of strata sequences and grain size, and a lithologic sequence of a defined sedimentary facies can affect the seismic velocity to a certain degree. Based on this law, we can identify sedimentary facies by use of seismic parameters. (5) Total porosity一layer velocity of a known oil一gas reservoir and cap model. Based on the logging velocity, density and porosity of a known oil一gas source,reservoir and cap layer, associated with the real (practically measured) parameters such as density, porosity and permeablility, two explainning models of ve- locity一mud一sand contents and velocity一total porosity can be directly and statistically erected. This method is more .suitable and practical than the Wyllie equation and Cokriging statistical technique in the study of terrigenous sedimentary basins.