Improved SAGD (steam assisted gravity drainage) algorithm based on Kalman filtering

Abstract

The invention relates to the technical field of positioning a magnetic field. An improved SAGD (steam assisted gravity drainage) algorithm based on Kalman filtering comprises the following steps of: 1, selecting a plurality of target points as reference points relative to navigation positioning, wherein the interval space of the target points is four times of a predetermined double well distance Delta1; 2, placing a magnetic sensor at the target point of which the footage is z2, the drill footage z1 is changed to the position of z2+2Delta1 from z2-2Delta1, recording field data of the whole operating distance by the magnetic sensor, and inputting a magnetic field model; 3, calculating according to the known double well footage z1 and z2 to obtain a plurality of r values; 4, resolving a plurality of vertical bias angles Theta of two opposite wells according to the magnetic field model; 5, inputting the r and Theta values of a plurality of measuring points into a Kalman filter, and performing next precasting according to a certain state transition rule; and 6, performing filtering updating on r and Theta to obtain filtering evaluate, and repeating steps 5 to 6 until all the measuring points are input, and the filtering evaluate is the final positioning result. By the method, the continuity and anti-noise and anti-interfere performance in drilling process can be guaranteed.

Description

technical field [0001] The invention relates to the technical field of magnetic field positioning, in particular to proposing an improved algorithm based on Kalman filtering based on the shortcomings of SAGD technology for ranging and guidance under low signal-to-noise ratio or sudden interference. Background technique [0002] According to statistics, the reserves of heavy oil, super heavy oil and natural bitumen in the world are about 1000×10 8 t, accounts for a large proportion of the total oil and gas reserves. For countries such as China, the United States and Canada, which are relatively rich in heavy oil resources, how to economically and effectively exploit heavy oil has become a major issue in the petroleum industry. Traditionally, heavy oil is exploited by thermal oil recovery, including steam injection, steam flooding and other technologies, which are very successful in the exploitation of ordinary heavy oil. However, the traditional method for subsurface crude o...

AI Technical Summary

Problems solved by technology

However, this algorithm is solved by only one measurement of the magnetic field at a specific position during the drilling process of the drill bit. In the case of low signal-to-noise ratio or sudden interference, the accuracy of its positioning results will be deteriorated

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