The Design Of Drainage Equipment For Unconventional Gas Based On Velocity String Technology

The thesis was supported by the projects which are “ Research and Development of Key Equipments of the Same Well,Multi gas production" of the National Oil and Gas Science and Technology Project(No.2016ZX05066-004-002)” “Research on High Efficient Dewatering Gas Production Technology for CBM Wels on LiuLin Demonstration Area(No.2011ZX05062-004)” and “Research on the Design of Bottom-Hole Pump Technology for the Drainage of CBM Wells(No.51174224)”.With the analysis of the characteristics of CBM drainage and the laws of the water production and gas production of CBM reservoir,based on the careful study of the gas generation characteristics of high pressure gas reservoirs and the water and gas production rules of low pressure coalbed gas reservoirs,with the analysis of velocity string technology and drainage conventional three-mining equipment,this thesis proposed scheme commingled device based on the velocity string coal formation process multiple gas according to coal mining gas discharge energy,a continuous,steady requested.For low pressure CBM,proposed the scheme of the well kept continuous production process by artificial lift-velocity string technology.The research gives the design scheme of velocity string suitable for the continuous discharge of coal-bed gas wels under different pressures,gives drainage program of high pressure gas carrying low pressure water and the scheme of the continuous conversion of CBM artificial lift to the velocity string program.The application of the above device can effectively prolong the period of high and stable coal-producing gas wells and improve the development benefit of coal-bed gas reservoirs.Firstly,this thesis summarizes the current production operations in the conventional three pumping equipment coal gas wells into the stable production of the mining situation,analysis the reasons of the high yield short-time,difficult to steady production for a long-term.Clarify the feasibility of using velocity string technology for coal gas wels.According to the gas drainage of high and low pressure coal series respectively,the design technology of velocity string production technology applied to the drainage and gas production of the corresponding gas reservoirs is put forward.Secondly,the calculation method of critical gas production rate and gas production rate for the production of coalbed methane wels is given in this thesis.According to the tubing design theory,the nomogram of velocity string column for site design and application is given,and according to the critical gas production calculation method combined with the Hagedon model,design a velocity string selection method based on the daily output of water.At the same time based on the above theory,finish the programming design of key parts selection process.Thirdly,according to the production of high and low pressure gas reservoirs,this paper analyzes the feasibility of applying the velocity string technology in coal-bed gas wels by investigating the production characteristics of unconventional coal gas and the principle of velocity string production technology in the production of conventional oil and gas wells.Combined with the current use of the conventional triple-drained mining equipment in coalbed methane wels,a design scheme of high and low pressure gas combined mining based on velocity string extraction is proposed,and the related conversion process flow is given.Completed the design verification of the key structure and flow field analysis.In the same way,aiming at the continuous drainage of low pressure gas reservoirs: According to the actual situation of CBM well drainage,the solution to maintain continuous production of gas wels is given and the design of continuous conversion pump based on artificial lift-velocity string technology is completed.Achieve a continuous state in the well,the artificial lift and velocity string technology for rapid and continuous conversion.The main achievements include: based on artificial lift-velocity string process continuous conversion pump overall operation process feasibility analysis,the overall process design,velocity string selection method design,conversion conditions analysis,continuous conversion pump structure design,the key device mechanics analysis,simulation check,assembly flow field analysis,the whole Assembly drawings and prototype manufacturing.Combined with the actual engineering,verify the practicality of the overall structure.Finally,according to the actual conditions of the project,according to the needs of the site,the overall assembly drawing of the continuous conversion pump for the artificial lift-velocity string process is drawn.Through the exchange with the manufacturers,the drawing of the entire production drawing was completed to meet the needs of the site.The extraction equipment and technology proposed in this paper have realized the continuous conversion of coal gas drainage and gas recovery from artificial lift to the use of the energy of coalbed methane production gas itself.For high-pressure gas to carry low pressure gas reservoir water drainage process can be fully utilized high-pressure energy,forming a highpressure gas carrying water production from the interior space,low-pressure gas production from the annulus of the "two pressure system" mode of production.Achieved the "two gas commingled" the established goal.For low pressure coalbed methane wels,it not only meets the requirement of small and discontinuous water production in CBM wells,but also achieves drainage without relative energy and no moving parts,which can effectively prolong the trouble-free operation time of drainage facilities in coalbed methane wels.This can avoid the damage to the CBM reservoirs.This design made a difference in extending high and stable production time.