Design Of EM-MWD Prototype For Deep Geological Drilling And Study Of Adjacent Well Receiving Method

With the rapid development of our national economy and society,demand and consumption for mineral resources increased year by year.Most of the country's shallow mineral resources of developed areas have been explored and tend to be exhausted,in the future,geological prospecting will undoubtedly expand to deeper and more complex strata,its depth is generally between 600 m and 2500 m,and is turning into deep holes above 3000 m.According to “geological core drilling regulations”(DZ/T0227-2010),the hole with depth between 1000 m and 3000 m is defined as a deep hole.In the proceeding of deep hole drilling,hole trajectory is an extremely important part,it not only directly affects the quality of the hole,but also directly affects the efficiency and safety of the drilling.With the continuous development of geological drilling,borehole depth tends to deeper,the quality of well inclination control requirements will be stricter,and the demand for measurement while drilling is also larger.EM-MWD,short for Electromagnetic Measurement While Drilling,transmits the information measured at the bottom of the well to the surface by low frequency electromagnetic wave.It has the characteristics of high signal transmission rate,no need for circulating drilling fluid to transmit data,short measurement time,no vulnerable components and low cost.In particular,the EM-MWD system is not affected by drilling fluid medium,it is not only applicable to the conventional drilling fluid,but also suitable for the gas and foam drilling mud,thus avoid the difficult problem which can not be solved by mud pulse measurement while drilling.EM-MWD products have been relatively mature in foreign countries,domestic oil research institutes and other companies have also developed corresponding products,but these products are still blank in the field of geological drilling.Therefore,keeping up with the trend of measurement while drilling technology,drawing lessons from domestic and foreign advanced MWD technology,combining the technology of the domestic geological drilling,taking advantage of own technical superiority,conducting research on EM-MWD for deep hole geological drilling.The complement of independent intellectual property rights,stable and reliable,flexible EM-MWD can avoid buying expensive measurement while drilling equipment from abroad and reducing the cost of drilling.This is of great significance to the rapid development ofEM-MWD technology in China and to related industries such as national geology,mining and petroleum.This paper analyzed and researched the EM-MWD prototype for geological drilling in deep hole and the technical problems of transmission distance extension methods for EM-MWD based on adjacent well down-hole receiving.It studied the key techniques of EM-MWD systematically,mainly including transmission channel model of EM-MWD,structural design of prototype,research on down-hole transmitter and ground receiver of prototype,installation error correction and temperature error compensation of measuring parameters,models and methods for EM-MWD transmission distance extension model based on adjacent well down-hole receiving,at last,carried out the down-hole testing of EM-MWD in drilling fields.The main research results and innovations of the thesis are as follows:1.To solve the structural strength problems of the EM-MWD prototype for deep hole drilling,a high strength insulated outer tube and a new inner tube structure were designed.Based on the comparative analysis of the existing insulated gap,a high-strength insulated gap structure was designed,according to the theoretical calculation and finite element simulation,the designed insulated gap meets the strength requirement of 100 k N pressure,40 k N tension and 15 k N·m torque.According to the characteristics of geological drilling,a new insulated inner tube structure was designed,based on the theoretical calculation and finite element simulation,the designed insulated inner tube met the requirement of static water column pressure of 40 MPa.What's more,a testing method of insulated inner tube was designed and the strength and seal performance of insulated inner tube were tested.Meanwhile,the strength of insulated gap was tested by the XY-4 core drilling rig.2.The down-hole transmitter and ground receiver of the EM-MWD prototype for deep hole drilling were designed,and the attitude parameters of the EM-MWD prototype were corrected.According to the EM-MWD working mode of down-hole transmission and ground reception,the down-hole transmitter and ground receiver were designed respectively,the error compensation of the measurement system was experimentally studied,and the performance of the transmitter and receiver was experimentally conducted indoors and outdoors.The reasons for errors of the EM-MWD measurement parameters were analyzed,and the error model was established.The installation error and the high temperature error were corrected.Through the error correction experiment,the absolute value of temperature error compensation of inclination angle was 0.137?,the absolute value of maximum installation error of inclination angle was 0.08?,both met the requirements of the designed accuracy.The indoor experiment of transmitting and receiving showed that,the designed down-hole transmitter sensor working normally,coding Manchester was normal,and the circuit worked normally under high-power transmission.Designed ground receiver Manchester decoding was correct,in the indoor environment with relatively small noise,the signal waveform of 5?V was relatively undamaged after amplification and filtering and other signal processing,and the received signals can be decoded correctly.The outdoor experiment of transmitting and receiving showed that,after low-pass filtering and power band notch,the power band interference was suppressed,the signal was ideal and the receiver could decode correctly.3.A method of transmission distance extension for EM-MWD was proposed based on adjacent well down-hole receiving.According to the equivalent transmission line,a kind of transmission model of the extension method was established.After the solving and simulation of the proposed model,the influencing parameters of ground receiving signal voltage were analyzed.At the same time,the influence factors by given adjacent well depth and given adjacent well distance of the voltage strength of ground receiving signal based on adjacent well down-hole receiving were analyzed.It was concluded that this method can effectively increase the receiving signal voltage strength as well as improve the maximum transmission distance of EM-MWD,and has a broad application prospect in offshore drilling,oil and gas network drilling,coal-bed methane drilling,geological drilling etc.4.Measurement experiments of the EM-MWD prototype and the depth expansion method based on adjacent well down-hole receiving were conducted in the holes of depth 300 m and 616m(actual measured depth were 292 m and 598m),respectively.The experiments showed that: the EM-MWD prototype can withstand at least the static water column pressure of 598 m,and can meet the sealing performance requirements of the equivalent depth,both can normally transmitted and received electromagnetic wave signals successfully;The signal acquisition,transmission,reception and other modules of the designed EM-MWD prototype worked normally and could be applied to the well-site drilling;the experimental measurement results were consistent with the established equivalent transmission line model,combining with the characteristics ofdrilling engineering,the presence of casing was beneficial for the receiving signal voltage;the depth extension method of EM-MWD based on adjacent hole down-hole receiving can effectively improve the strength of surface receiving signal voltage,which proves the feasibility of this method.