Study On Magnetic Guidance Positioning Technology With Small Well Spacing

Shale oil,as a new supplement energy which can replace conventional oil,has huge economic reserves and is an important energy strategic resource in our country.With low organic matter conversion rate,low porosity and poor fluidity,it is difficult to produce shale oil with high efficiency by conventional technology.In-situ development of shale oil is a new development mode of low carbon,environmental protection,economy and high efficiency,which is expected to be used in the development of middle and low maturity shale oil.This development mode requires the deployment of multiple Wells underground,and requires the spacing of each horizontal well to be controlled between 6 and 10 m,so it has high requirements on well trajectory and drilling accuracy.Conventional drilling technology cannot meet the requirements of such small well spacing and high precision drilling.According to the current research status of magnetic guidance,this paper establishes the long-distance needle threading magnetic guidance positioning algorithm model and the magnetic guidance positioning algorithm model of double horizontal Wells under the magnetic shield environment of metal casing and using software to program and simulate the algorithm,the data measured by the probe tube is substituted into the algorithm for iterative calculation,and the relative distance and angle between the magnetic nipple and the probe tube can be obtained.At the same time,the design and manufacture of the magnetic guide tool are completed,and the performance of the magnetic guide tool is tested.In addition,the experimental platform of magnetic guidance positioning technology was built,and the accuracy of the two magnetic guidance positioning algorithm models was verified by physical model experiment.Meanwhile,based on the magnetic stub size effect,the simulation model was used to guide the measurement of magnetic field signal strength at a long distance.The main conclusions are as follows:(1)The magnetic induction intensity on the surface of the magnetic core component of the magnetic sub decreases after high temperature baking,but can be restored to normal value after cooling.The triaxial magnetic induction intensity of the fluxgate sensor of the probe tube does not change significantly after high temperature heating.Therefore,the magnetic sub and probe will not lose performance under the condition of high temperature baking,and can still work normally.At the same time,the measurement accuracy of the attitude Angle of the probe tube is greatly improved after the orthogonal coaxial calibration.(2)In the experiment of magnetic guidance and positioning for long-distance needle threading,with the increase of the offset distance between the magnetic sub and the probe,the distance measurement error also increases and the measurement accuracy decreases.When the offset distance is constant,the distance measurement error decreases with the increase of the axial distance between the magnetic sub and the probe.With the pipe as the central axis,the positioning algorithm model in the sectors with 45° Angle spread to the left and right is more accurate,which can meet the drilling requirements with distance error less than 0.5m.(3)In the magnetic steering positioning experiment of double horizontal Wells,the distance between different dots has little effect on the distance measurement error,which is relatively small when the spacing between dots is 10 cm.Within 1m of the relative distance between the magnetic sub and the probe,the measurement error is inversely proportional to the relative distance,that is,the greater the relative distance,the higher the measurement accuracy,and the positioning error rate of the positioning algorithm model is less than 5%.(4)In the experiment of magnetic sub size effect,the total magnetic field signal intensity of magnetic sub is approximately equal to the vector sum of the magnetic field signal intensity of each magnet.When the number of magnets is constant,the magnetic field signal intensity generated by the magnetic sub detected by the probe decreases with the increase of the relative distance between the magnetic sub and the probe.In this paper,when the intensity of magnetic field signal generated by magnetic sub detected by the probe tube is greater than or equal to150 n T,it can meet the accuracy requirement of measuring error less than 5%.In summary,both the magnetic steering tool and the magnetic steering positioning algorithm model can meet the technical requirements of small well spacing and high precision drilling,and can provide good technical guidance for in-situ development of shale oil.