Sedimentary Facies Analysis Based On Spatial Information And Its Application

Sedimentary facies are the combinations of rock formed in certain palaeogeographic environment. In the traditional research of sedimentary facies, usually under the crops, cores, construction, bedding, the fossil remains, particle size analysis, logging debris and other information to determine the sedimentary facies, and then basing wells information to determine microfacies, and tagging these sedimentary facies and microfacies on the plan. The ultimate formation of the sedimentary facies model plans. This method of sedimentary facies analysis is not only time-consuming and laborious, but its shape to a large extent by the effect of artificially.With the development of computer technology, people consider the use of computer technology to solve the single well sedimentary facies identification, so that not only save a lot of time, but can exclude certain effect of artificially.Single Well computer analysis of the sedimentary facies have some relatively mature methods, for example, the expert system method and neural network method. However, these sedimentary facies analysis method is faster in the identification of sedimentary facies, it does not take into account the spatial distribution relations of wells in oilfield, and the sedimentary facies of the division had not better approach.In this paper, the author use two methods of spatial analysis in GIS, which are buffer zone analysis and overlay analysis. Analyzing the known sedimentary facies types of wells with buffer analysis and establishing the distribution of sedimentary facies boundaries through the use of different buffer radius. And set up a fan-shaped sedimentary facies, sheet sedimentary facies and banded sedimentary facies model of the buffer zone which can be applied to future plans of the sedimentary facies mapping work.The steps of this method are:⑴Considering different forms parts of a sedimentary facies,buffering every parts using different buffer radius and then every parts of the buffer regions formed;⑵Stacking different parts of buffer zone according to thesedimentary sequence, and considering banded sedimentary facies coverage in fan sedimentary facies, fan-shaped sedimentary facies cover sheet in the sedimentary facies. Eventually, all the buffer zones will stack together form a planar map is a complete plan of sedimentary facies.The sedimentary facies analysis method based on the spatial information can achieve the following functions:⑴The correction of sedimentary facies between wells, including sedimentary facies bound test, verification and correction of single well and inter-wells;⑵Spatial distribution analysis of sedimentary facies, including the inter-well and unknown region of sedimentary facies analysis and forecast palaeogeographic environment;⑶Establishing of regional sedimentary facies distribution plane with the sedimentary facies analysis, and forecasting the favorable regions of litho-stratigraphic reservoir.Analyzing the sedimentary facies of Kong 2 Member in Kongnan area with this method and map out a plan of of Kong 2 Member which have certain similarity compared to the sedimentary facies map made by the artificial in general trend and distribution. However, the use of spatial analysis methods of sedimentary facies plan and the artificial method of deposition phase diagram there are differences:⑴Rivers elongation generated by the artificial is better than which made by the Computer method. This was mainly attributable to the computer needs strict implementation of whether the two wells connected by the river, while artificial methods have greater flexibility;⑵Maps generated by the Computer method and by the artificial have some difference in the connection of river.⑶Sand sheet distribution in computer-generated map is strictly accordance with the scope of neighborhood wells buffer forecast while the drawing of sand sheet body with greater distribution of randomness.