Research On Magnetic Positioning Method Of Adjacent Well Spacing In Cluster Wells

Cluster wells can effectively improve the ultimate recovery of oil fields,and ensure the production of single-well crude oil.The technology of magnetic positioning drilling is one of the fine control techniques in the cluster wells,and the adjacent wells spacing positioning is the core of fine control technology of cluster wells.At present,there is no self-developed and technically perfect cluster wells magnetic positioning technology for its adjacent wells anti-collision ranging field in our country,while corresponding measurement and control instruments have been developed and applied in actual drilling engineering in foreign countries.Based on the analysis of the principles and advantages and disadvantages of the existing magnetic positioning technologies of adjacent wells spacing,this thesis focuses on the active magnetic positioning drilling anti-collision detection technology of cluster wells and proposes two new adjacent wells spacing measurement schemes of active magnetic positioning for different application scenarios.Namely,the adjacent wells spacing measurement method of cluster wells with asymmetric positive and negative magnetic sources excitation applied to the offshore drilling platforms,and the adjacent wells spacing measurement method of cluster wells with current excitation applied to the land well factory.The inter-wells positioning signal detection algorithms corresponding to the above mentioned adjacent wells spacing measurement methods are proposed,respectively.Firstly,the design schemes and working principles of the two new adjacent wells spacing measurement methods are elaborated,respectively.Secondly,the magnetic field distribution around the ferrous casing is revealed by using magnetic dipole structuring method,the segmentation method of ferrous casing is designed,and calculation formulas of the adjacent wells spacing measurement are derived separately.Thirdly,the several main factors affecting the measurement results of the two new adjacent wells spacing measurement methods are studied by numerical simulation,and the rules are summarized.Finally,the application scopes of adjacent wells spacing measurement schemes are summarized,the first scheme applies to the case of existing well around the drilling well,and the second scheme is suitable for the case of multiple existing wells around the drilling well.Given the inter-wells positioning signal characteristics of adjacent wells spacing measurement method of the cluster wells with asymmetric positive and negative magnetic sources excitation,the frequency spectrum focused discrete Fourier transform(FFDFT)and the automatic segmentation improved Quinn-Rife(ASIQ-Rife)signal detection algorithms are proposed respectively.The accuracy of FFDFT interpolation algorithm is much better than of discrete Fourier transform(DFT)algorithm;The accuracy of ASIQ-Rife interpolation algorithm is better than that of Rife interpolation algorithm and Quinn interpolation algorithm.The accuracy of FFDFT interpolation algorithm is higher than that of ASIQ-Rife interpolation algorithm,while the computational complexity of ASIQ-Rife interpolation algorithm is lower.Therefore,in practice,reasonable algorithm selection and application can be carried out according to the requirements of accuracy and real-time.The above algorithms provide reliable algorithm support for the subsequent inter-wells positioning and ranging.Given the adjacent wells spacing measurement method of cluster wells with current excitation,the optimal excitation current waveform and signal detection algorithm are proposed respectively.The zero-crossing square wave with the maximum fundamental power as the optimal criterion is proposed as the excitation waveform.The fundamental power of the square wave accounted for 92.26% of the total power.Using the optimized zero-crossing square wave not only facilitates the development of high-power current sources but also simplifies the subsequent signal processing.The feasibility and accuracy of the method are verified by simulation experiments,which provides theoretical guidance for the development of anti-collision instruments for magnetic positioning drilling in cluster wells.