Mechanical Wireless Inclinometer-Principle, Design And Application

In order to overcome the shortage of existed techniques for measuring deviation of oil well and to meet the requirement of complex vertical wells, research on a new technology which measure the deviation of vertical wells while drilling by mechanical apparatus is performed and an innovative design scheme of the Mechanical Wireless Inclinometer(MWI) was presented. Based on the investigation on principle for measuring the deviation, technique for information transition and control, theory of mud pulse transmission, principle of pulse generator and design method of the key mechanisms including the deviation-measuring unit, the mechanical coded control unit and the mud pulse generator, a new type of MWI was developped successfully. The main work is summarized as follows1 Research on Design Scheme of MWIBased on the innovative idea, research on technique for measuring the devition of the vertical wells using mechanical apparatus was carried on and a design scheme of MWI was presented, by which the downhole apparatus is a mechanical unit, measuring the deviation by precise mechanism and transferring the information from bottom of the well to ground by mud pulse technology. Considering the design and manufacture of MWI and the requirement of drilling engineering, the technical parameters and the detailed implementary schemes of the key techniques such as measuring the devition, generating the pulse and corresponding relation of the inclination and the pulses were presented.2 Research on Theory of Mud Pulse Transmission and Design Method of Pulse GeneratorDrilling fluid mainly consists of liquid, solid and a little air. Regarding drilling fluid as one dimension bogus homogeneous flow, a formula for calculating transfers speed of mud pulse was derived. Analysis on influence of various factors to speed shows that the content of liquid, solid, gas influenced the speed and the influence of gas is most serious.By applying the method for transient analysis of waterhammer, the basic equations for describing the transient characteristic of mud pulse were established and the equations can be solved by using method-of-characteristics. The simplification model for drilling fluid circulation system with pulse generator was set up, dividing the circulation system into five sections: from mud pump to air tank, from air tank to dilling pipe, from drilling pipe to drilling collar, from drilling to pulse generator, from pulse generator to bit. Based on analysis on the boundary conditions of every section, the computer program to solve the basic equations using the method-of-characteristics and method-of-difference was designed. Analysis result shows that attenuation will occur during the pulse transmission in drilling fluid. The amplitude and frequence are two important characteristic of mud pulse. Attenuation law of mud pulse was studied. analysis on various factors influencing attenuation shows that frequence of pulse and viscosity of drilling fluid affect attenuation of pulse seriously.Positive pulse signal was adopted to transmit information from bottom of the well to ground and a simple reciprocating throttled positive pulse generator was developed. The principle and design method of pulse generator were investigated. A damper providing work condition for pulse generator was designed, analyzing the damping characteristic of the damper and its effect to pulse generator. Method for calculating the amplitude and frequence of pulse was studied. and the relation between amplitude, frequence of pulse and drilling fluid displacement was obtained. It could be guidance for design and application of pulse generator. The process of generating the pulse was simulated using FEM to understanding the amplitude of pulse and the force that drilling fluid act on the pulse valve. Comparison shows that result of simulation was better than theoretical calculation. Finally, the structure of the reciprocating throttled positive pulse generator was optimized.3 Research on Techniques for Deviation Measurement and Information Transformation Based on the gravity principle, a mechanism called deviation-measuring unit, which consists of a pendulum and a sries of graduated stop shoulder, was developed and the method for structure design and calculation of the unit was presented. Structure simulation on deviation-measuring unit shows that the best precision of the unit is 0.2°, and the unit's structure size influence the precision and measurement range of the unit markedly. The structure pasrameter should be determined according to the precision and reliability of the unit and field requirement.The way of information transforming is realized by a mechanism called mechanical coded control unit, which transform the inclination information into variety of displacement and enlarge it, the enlarged displacement can control pulse generator to produce pulses. The principle and structure of the mechanical coded control unit were described. Based on the analysis on kinematic relation of all parts, the method for structure design and calculation was given. Assembled structure of the deviation-measuring unit and the mechanical coded control unit can achieve the function of measuring the deviation and transforming the information. 4 Development of MWI and Its ApplicationBased on all these research, the whole structure of MWI with a self-compensating constant-pressure-difference seal system was developped successfully. Lab and field test shows that all the performance and index of MWI attain the expected purpose, and it can satisfy the demand of measuring the deviation of vertical well while drilling, especially to high temperature & high pressure well, deep well and super-deep well because of its very good anti-heat capability and field applicability. It has a good application in 40 oil wells and set up the record for measuring deviation in heat well, high pressure well and deep well, which produce remarkable economic and social benefit.