The Study Of Boundary Recognition Of Gravity Data And The Application In Oil And Gas Exploration

This thesis topic is derived from Geological Survey projects in China about the task “in the key areas of the Yangtze and gas geological-geophysical interpretation”(item number 1212011220750-03),which is part of the geologic integrated research of Marine oil and gas of Upper middle yangzi key area and the evaluation of this district.Upper Yangtze is located in a low-latitude region of the world's leading oil and gas enrichment zone around the world,which is similar to the the geological background of global Marine oil and gas,and this district has good resource base and accumulation conditions.After more than 40 years of exploration and research,we found that Marine strata in southern China was a potential hydrocarbon-bearing zone.In the view of the complex geological conditions in the study area surface and large undulating terrain,these caused great difficulties for dividing the fracture and delineating the hydrocarbon potential.Compared to other geophysical data,gravity data have a stronger lateral resolution ability,and have a greater advantage in describing the change of geological characteristics the in the horizontal plane.Therefore,the use of gravity data to extract structural characteristics,determine the geological structure of the horizontal position or the projection position on a plane,is an important part of the data processing and interpretation of gravity.Currently,we have made a lot of achievements in using gravity data to research the structure in the distribution plane and extended features.Commonly,to extract or enhance the geological structure features or boundaries is called boundary recognition method.Boundary recognition clearly reflects the line between the formation and distribution range of body.Therefore,Using gravity data of the border recognition method has obvious practical significance in analyszsing of the fracture plane,distributing division of geological structure and delineating of hydrocarbon plays,etc.However,in most geological environment,due to the geological buria depth and the weakness of the abnormal signal at the target body,coupled with other factors,such as noise interference,the normal extraction of geological information may cause some difficulties So we need to study how to efficiently extract weak anomalies and reduce the influence of noise in order to effectively reflect the subsurface location information,to determine the purpose of the underground geological boundary.To solve these problems,this paper studied the following:This paper analyzes several common kinds of the basic principle boundary identification method of the gravity data,such as the normalized total level derivative vertical derivative method,the analytical method of signal amplitude,tilt angle and its horizontal derivative,Theta method etc.A typical model were studied by these methods are gravity data and applications the ability to distinguish the effect of boundary identification in a single model,combined model and noisy models.Then,we Summarized and analyzed each kind of recognition method effection and the advantages and disadvantages to improve the applicability and effectiveness of these methods.On the basis of recognition results summarized above several common boundary identification methods,according to the characteristics of the ability to resist noise is generally weak,this paper proposes a stronger noise reduction and new methods to identify the boundaries accurate boundary extraction: the eigenvalues of the structure tensor method.Through the design of three kinds of typical model trial,we analyze and spreadsheet of applying effects,and other parameters of the law of the eigenvalues of the structure tensor method and the several common methods to prove the eigenvalues of the structure tensor method more effective.This paper will also apply boundary identification method to the gravity data processing in the Yangtze region using the total horizontal derivative,the tilt angle and the tilt angle.These results show that these methods can provide more information and evidence to find fault or tectonic boundary,and more accurately divide and reflect the main faults or tectonic boundary in the Yangtze region.