| With the continual exploration of international oil and coal resources, the price of crude oil is increasing continually. Therefore, the importance of the coal bed methane (CBM) resources can not be over estimated as a kind of economical and environment friendly resources. At the same time, the exploration and utilization of the coal bed methane can not only release the oil and coal resources shortage crisis but also benefit the full and safe coal exploration and decrease the air pollution caused by the methane discharge. So, to encourage and strengthen the coal bed methane exploration, many countries such as United States, Australia, Germany, England and Russia issue a series of related policies to encourage the enterprises to participate in CBM exploration. Now, the exploitation and research on exploring the coal bed methane is becoming a hot issue all around the world. And the new technology of exploration has been revived continually such as Horizontal Directional Drilling and Oriented Pinnate Horizontal Multilateral Drilling, Hydraulic Pressure Fracturing Technology, Displacement of Multi-gas, Coalbed Methane Estimation While Drilling and etc. All these stimulation technologies can improve the yield of coalbed methane and the further investment has been done to investigate new kind of exploration and utilization technology.From the 2005 national coalbed methane resource assessment, the total coalbed methane resource under less than 2000m depth is 36.81×1012m3, among of which can be exploited is 10.87×1012 m3. Nevertheless, compared with developed countries such as United States, our technology on exploring coalbed methane lags far behind because our research on this field started comparatively late. Another reason is that there is no consistent view on coalbed methane exploitation among state and large coal fields. Therefore, related technologies have not been developed maturely and have not been industrialized in large scale.Nowadays, energy sources shortage, coal mine safe production and environment protection all call an effective exploitation of coalbed methane. Our government and coal mines have been coming to pay more attention to the importance of developing the related technology on coalbed methane production. Hence, a series of policies have been made to support research on this field such as National Coalbed Methane Development "the Eleventh Five-Years Plan", State Council Document on further standardize coalbed methane industry and some great special funds including national "863 program", "973 program" issued. All these provide a much more favorable condition for the coalbed methane production and utilization. All these beneficial conditions promote our CBM development dramatically. Now, many areas such as Qinshui Basin, Eerduosi Basin, Ningwu Basin and Zhungeer Basin etc. have constructed developing demonstration bases. Among of them, the Lanyan Coalbed Methane Corporation has constructed the first commercial coalbed methane production demonstration center.Based on this background, the in-situ exploration technology and hydraulic correction technology for CBM subhorizontal drilling is put forward in this paper. By using subhorizontal hole and its branch hole, the technology of exploring CBM under the well of the coal mine has come into the practical application and brought about super recovery effect. However, the related theory, technology and equipment are still at research developing stage and needed to be improved to enhance the ratio of utilizing of recovery and achieve the national standard of methane discharge to ensure the safe exploitation of coal mine.To achieve this goal, a full detail distribution of CBM in the coalbed should be obtained. And a full understand of CBM concentration in different area of coal bed should be prerequisite to supply original data for safely exploring plan of coal and CBM, which also meet the need of the national policy about keeping CBM data every 50m in hand. For this reason, Based on the vast investigation on the Qinshui Basin, the research team, which author has participated in, put forward the research project on the in-situ exploration and hydraulic correction technology for CBM subhorizontal drilling and succeed in applying "863 Program" "Jincheng CBM Exploitation and Production Stimulation Technology Program" (20060106Z2005) .As the hole deflexion or even intercross with each other can not be avoided when coal bed has been drilling for hundreds or thousands of meters during subhorizontal drilling, which made discharge repeat in some area while no discharge done in other area, which will influence the CBM recovery ratio dramatically. And this discharge will result in misunderstanding on CBM discharge rate and leave some safety problem in coal exploitation, which also make against to the in-situ exploration of CBM. So, how to ensure better subhorizontal drilling quality is urgent to be solved. After analyzing current directional drilling technology in coal mine and combining with coal bed geological feature, hydraulic condition influencing hole deflexion, hydraulic directional water jet fracture mechanism and trenchless directional drilling principle, a more economical and suitable hydraulic correction scheme is put forward in this paper to ensure the subhorizontal drilling hole meet the design requirement of CBM discharge hole. For the further study in this field, author succeeded in applying the Research Foundation for Out-standing Young Teachers of China University of Geosciences "Coal mine subhorizontal drilling hydraulic correction technology" in 2005. After some research of theory and experiment, author succeeded in applying National Natural Science Foundation of China "the research on the deflexion analysis and hydraulic correction theory for coal mine subhorizontal drilling" in 2007 in order to do some further research in this field. These two technologies, independent and also correlated in some area, are the key technologies and new research direction in the field of CBM subhorizontal drilling. For recent years, author and research team coworkers have plunged large amounts of spirit and time in developing these two technologies. Combined with coal mine geology, drilling technology, mechanical design and manufacture, sensor technology, measuring technology, electron circuit, computer program, horizontal directional drilling, hydrodynamics mechanics, water jetting technology and other theories and technologies, some research has been done by adopting theory analysis, product made, indoors experiment and site experiment.CBM in-situ exploring technology mainly includes design and manufacture of the hydraulic packer and detection and sampling system. During process, a silica gel capsule is designed specially to meet the need of hydraulic seal, and a single channel two-way valve, used as second pressure seal and unset of hydraulic packer, is designed and manufactured. A hydraulic packer and detecting and sampling cavity are designed. By using an A/D collection card, a pressure collection system is made, and a visual program is designed for pressure test indoors, an optimal choice is made in choosing pressure sensor, concentration sensor, temperature sensor, microprocessor chip and related electronic component and a related circuit and data collection and storage system are designed. At the same time, a micro electromagnetic valve is refit to control the open and close of the vacuum gas collecting bottle. Besides these, an embedded system software is designed to collect and transmit data which can be displayed on the computer screen by chart and diagram or figure. During hydraulic correction process in practice, a theory analysis is made for directional water jetting drilling tool design based on the analysis of deflexion mechanism of coal mine subhorizontal drilling and hydraulic directional water jetting fracture coal body mechanism. A special hydraulic directional water jetting drilling tool is designed and applied an invention patent.During test, repeated indoors test have been done to test seal capsule of hydraulic packer, seal pressure, unset pressure, pressure keeping time and hydraulic pressure test and control. Meanwhile, data collections have been done indoors many times for the detection and sampling microprocessor system. Therefore, an ideal effect is obtained during field test combining with these tests. In practical engineering test, a satisfied effect of hydraulic directional water jetting technology applied in practical horizontal directional drilling has been obtained and verified and hydraulic correction test data have been derived, which can reflect that both coal mine subhorizontal drilling in-situ exploring and hydraulic correction technology can achieve the expectant research aim and can be applied in engineering practice.Based on the theory and practice research, a systematic and comprehensive analysis about CBM subhorizontal drilling in-situ exploring and hydraulic correction technology is made in this paper. The main work is as follows:Chapter 1: this part is introduction. The current situation of drilling and exploring, detection of CBM and horizontal directional drilling of CBM at home and abroad is introduced in this part. Based on this research background, a research on CBM subhorizontal drilling in-situ exploring technology and hydraulic correction technology is put forward. At the same time, a general scheme of combined application of CBM subhorizontal drilling in-situ exploring and hydraulic correction technology is put forward in this part. And three key technologies such as downhole in-situ hydraulic seal, in-situ exploration and sampling and hydraulic correction are introduced respectively. Besides, the principle and detail research content of these key technologies are also introduced. Furthermore, this part also analyzes the research purpose and significance.Chapter 2: this part mainly introduces detail process of in-situ exploring and CBM collection technology and apparatus. Based on the analysis of different seal schemes, a downhole hydraulic seal technology is ensured to realize downhole seal for in-situ exploration. A better choice and refit for a silica gel seal capsule with super performance has been done. And according to character of the single channel for seal and unset, a secondary hydraulic single channel two way valve is designed, calculated theoretically and tested to make sure secondary hydraulic pressure. At the same time, a digital computation model for hydraulic pressure loss is established and a visual computation program is designed to test and control of input pressure outside the drilling hole. Based on the measurement principle of pressure, concentration and temperature, a better choice on sensors for CBM pressure, concentration and temperature is made and special servo circuits, timing sequence control circuit, electricity detection circuit, data collection and storage system and electromagnetic valve control circuit has been made. Besides, embedded system software has been programmed. The detection and sampling cavities are designed according to the requirement of detection system. After confirmation of electromagnetic valve + vacuum CBM gathering bottle scheme to get the coal bed methane sample, a vacuum gas gathering bottle, electromagnetic valve joint and vacuumzed joint are made. Finally, the process of gathering scheme is set down.Chapter 3: this part mainly introduces the research process of hydraulic correction technology. Based on subhorizontal drilling deflexion mechanism and hydraulic directional water jetting fracture coal body mechanism, the diameter caculation method of jetting nozzle, a key part of hydraulic directional water jetting technology, has been arrived. After analyzes the directional principle, a hydraulic water jetting drilling tool is established. Finally, based on the analysis of principle of self-oscillating pulsed jet, the drilling tool of tapered nozzle series connecting self-oscillating pulsed jet nozzle is designed.Chapter 4: this part mainly introduces test process of in-situ exploring technology indoors and in field. Tests on seal capsule, seal pressure, unset pressure and pressure keeping time of hydraulic packer has been done repeatly in order to obtain the optimal value of testing parameters. By using pressure sensor, A/D collection card and computer, accurate test and control of hydraulic pressure have been done succeed. Many times of data collection and reliability test indoors on methane concentration and pressure have been done to examine the detection and sampling microprocessor system by using coal methane, air conditioner outlet and heater as test object. And in field practice, coal bed methane horizontal drilling in-situ exploration test has been done with the result of ideal test data and perfect effect.Chapter 5: this part mainly introduces the test process of hydraulic correction technology indoors and in field. Among indoors tests, main works are the optimal choice and verification for the jetting nozzle of the hydraulic directional water jetting. And in practical application test, hydraulic directional water jetting correction technology has been applied in practical horizontal directional drilling engineer with satisfactory correction effect. The related correction test data obtained has been analyzed in this part.Chapter 6: this part is conclusion. This part mainly introduced the achievements obtained and main creative work after theory and practice research. Then the limitation of this research work and the further research that should be done are also pointed out. Finally, the prospect of our national coal bed methane industry and related technology is put forward in the end of the paper.In a word, a series of practical research have been done to meet the need of coal bed methane industry and some achievement has been obtained. It is also the result of succeed application of many subject theories and technologies. From the obtained result of theory and test research, a prospective research goal of CBM subhorizontal drilling in-situ exploring technology and hydraulic correction technology has been achieved. However, as the key technologies of these two coalbed methane subhorizontal drilling are creative things, there are not any experience used for reference. Besides, the in-situ test condition can also bring the some limitation of this research. So, there are still many related research work should be done furthermore.
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