| Geosteering is an important measurement control technology in horizontal well and other drilling engineering.As one of the important technical supports of geosteering,logging while drilling near bit measurement can obtain various downhole parameters in time.Through the interpretation of logging while drilling data,high pressure formation prediction and formation lithology evaluation can be carried out,so as to guide production decision.However,due to the limitation of complex underground environment,the information uploaded to the ground is less,which makes the formation interpretation more difficult.In addition,the energy of logging personnel is limited,so it is difficult to accurately evaluate the formation and make decisions in real time for a long time.On the other hand,with the rapid development of computer technology,especially intelligent technology,its application in the field of oil and gas resources is becoming more and more in-depth,It is also a research direction of geosteering logging technology.Based on the azimuth-while-drilling gamma data,after research and analysis,a real-time stratum structure interpretation method is proposed: first,preprocess the gamma data,enhance the data information and get the gamma imaging results;then,through intelligent algorithms such as filtering,wavelet transform modulus maximum and Lee’s index,the dynamic threshold calculation of the gamma image is completed,and the preliminary division result of the formation boundary and the boundary contour set are obtained;finally,the formation recognition based on the LSTM model is established to determine whether the boundary contains stratigraphic information,and the contour point set of each boundary is fitted by the nonlinear least square method to obtain the corresponding sine information,which completes the interpretation of the relative structural dip of the strata.At the same time,according to actual application requirements,with related algorithms as the core algorithm,a real-time azimuth-while-drilling gamma logging interpretation auxiliary system was designed and developed.In order to verify the overall effect of the method,this article analyzes the accuracy and effectiveness.Through the interpretation of the forward data,the eight-channel gamma data of the well completion and the field data,it is verified whether the effect of the method can reach the expectation and whether it has the ability to be applied to the actual engineering to assist the logging personnel.The results show that the absolute error of dip angle calculation is less than 1° in forward data,the formation recognition rate is 92% and the accuracy rate of dip angle calculation is 96.6% in eight-channel gamma ray data of well completion,the average error in field application data is about 1.4° and the total time consumption is about 0.44 s.At the same time,the functions and user interaction of the logging interpretation assistant software system are tested,and the design objectives and requirements are achieved.The research on the interpretation method of formation structure while drilling combined with the intelligent algorithm and the design of auxiliary software system provide information technology support for the geosteering while drilling,and carry out beneficial exploration for the application of new computer technology in the field of oil and gas resources,which has practical application and promotion value. |
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