The mathematical model of dynamic loads was developed based on an analysis of the polished rod load of beam pumps, and the variation of the dynamic loads and the computation of the minimum and maximum limits during a ...The mathematical model of dynamic loads was developed based on an analysis of the polished rod load of beam pumps, and the variation of the dynamic loads and the computation of the minimum and maximum limits during a complete pumping cycle were given out by solving the model.Field examples verify that it is necessary to take into account the inertial and vibration loads while calculating polished rod loads.During the prophase of the pumping production, the dynamic to polished rod load ratio is relatively large.Then the ratio decreases rapidly and becomes small after entering stable production.Moreover, the total deformation of rod and tubing in CBM wells is much smaller than that in oil fields, and the deformation caused by the dynamic loads is also relatively small.The result of this work is the calculation of the dynamic loads.The application of this calculation for the sucker rod pumping system in CBM wells can give the desired accuracy of polished rod load and the dynamometer cards, which provides a reasonable basis for the design and selection of beam pumps.展开更多
At present,the aeration-assisted cutting-carrying technology is faced with complexities in the drilling of CBM multi-branch horizontal wells.For example,the aerating pressure is hardly maintained,and the borehole inst...At present,the aeration-assisted cutting-carrying technology is faced with complexities in the drilling of CBM multi-branch horizontal wells.For example,the aerating pressure is hardly maintained,and the borehole instability may happen.In view of these prominent problems,the technology of double casing tubes&a binary cycle system suitable for CBM multi-branch horizontal wells was developed according to the Venturi principle by means of parasitic tube insufflation which is used for well control simulation system.Then,a multiphase flow finite element model was established for the fluid-cutting particle system in this drilling condition.This technology was tested in field.Double-casing tubes cementing is adopted in this technology and a jet generator is installed at the bottom of the inner casing.In the process of drilling,the drilling fluid injected through double intermediate casing annulus is converted by the jet generator into a high-efficiency steering water jet,which,together with the water jet generated by the bit nozzle,increases the fluid returning rate in the inner annulus space.It is indicated from simulation results that the cutting-carrying effect is the best when the included angle between the nozzle of the jet generator and the vertical direction is 30°.Besides,the influential laws of cutting size,primary cycle volume,accessory cycle volume and drilling velocity on hole cleaning are figured out.It is concluded that this technology increases the flow rate of drilling fluid in annulus space,the returning rate of drilling fluid significantly and the cutting-carrying capacity.It is currently one of the effective hole cleaning technologies for CBM multi-branch horizontal wells where fresh water is taken as the drilling fluid.展开更多
It is of great significance to study the controlling effect of sealing systems on CBM enrichment in coalbed methane (CBM) exploration anddevelopment. In this paper, the relationships between CBM enrichment and geologi...It is of great significance to study the controlling effect of sealing systems on CBM enrichment in coalbed methane (CBM) exploration anddevelopment. In this paper, the relationships between CBM enrichment and geological elements were analyzed. The geological elements includesealing layers (e.g. regional cap rock, regional floor, and immediate roof and floor), later structural adjustment and strata production status. It isshown that CBM tends to enrich in the areas where regional mudstone cap rocks and floors are distributed stably, structures are uplifted andinversed slightly after the hydrocarbon accumulation period and the strata is gentle in a balanced state. Then, the concept of sealing system wasput forward based on the worldwide CBM exploration and development practices over the years. A sealing system refers to a geological unitcomposed of a lateral stable zone and cap rock which prevents gas from migrating upward and downward. In a sealing system, CBM can getenriched and coal-measure gas can also be accumulated. Finally, three gas reservoir types (i.e., sandwich-type CBM reservoir, associated CBM-sandstone gas reservoir and coal-derived sandstone gas reservoir) were identified based on the configuration relationships between elements ofthe CBM (or coal-measure gas) sealing system. It is recommended to change the exploration ideas from simple CBM exploration to 3D CBMand coal-measure gas exploration. In addition, an evaluation index system of CBM (or coal-measure gas) geological selection was established. Itis pointed out that good application effects may be realized if the stereoscopic CBM and coal-measure gas exploration is applied in the JunggarBasin and the eastern margin of the Ordos Basin.展开更多
基金Supported by the National Science and Technology Special Project of China(2008ZX05038-004)Shandong Province Science and Technology Development Project(2009GG10007008)
文摘The mathematical model of dynamic loads was developed based on an analysis of the polished rod load of beam pumps, and the variation of the dynamic loads and the computation of the minimum and maximum limits during a complete pumping cycle were given out by solving the model.Field examples verify that it is necessary to take into account the inertial and vibration loads while calculating polished rod loads.During the prophase of the pumping production, the dynamic to polished rod load ratio is relatively large.Then the ratio decreases rapidly and becomes small after entering stable production.Moreover, the total deformation of rod and tubing in CBM wells is much smaller than that in oil fields, and the deformation caused by the dynamic loads is also relatively small.The result of this work is the calculation of the dynamic loads.The application of this calculation for the sucker rod pumping system in CBM wells can give the desired accuracy of polished rod load and the dynamometer cards, which provides a reasonable basis for the design and selection of beam pumps.
基金supported by the National Science and Technology Major Project(No.2011ZX05061).
文摘At present,the aeration-assisted cutting-carrying technology is faced with complexities in the drilling of CBM multi-branch horizontal wells.For example,the aerating pressure is hardly maintained,and the borehole instability may happen.In view of these prominent problems,the technology of double casing tubes&a binary cycle system suitable for CBM multi-branch horizontal wells was developed according to the Venturi principle by means of parasitic tube insufflation which is used for well control simulation system.Then,a multiphase flow finite element model was established for the fluid-cutting particle system in this drilling condition.This technology was tested in field.Double-casing tubes cementing is adopted in this technology and a jet generator is installed at the bottom of the inner casing.In the process of drilling,the drilling fluid injected through double intermediate casing annulus is converted by the jet generator into a high-efficiency steering water jet,which,together with the water jet generated by the bit nozzle,increases the fluid returning rate in the inner annulus space.It is indicated from simulation results that the cutting-carrying effect is the best when the included angle between the nozzle of the jet generator and the vertical direction is 30°.Besides,the influential laws of cutting size,primary cycle volume,accessory cycle volume and drilling velocity on hole cleaning are figured out.It is concluded that this technology increases the flow rate of drilling fluid in annulus space,the returning rate of drilling fluid significantly and the cutting-carrying capacity.It is currently one of the effective hole cleaning technologies for CBM multi-branch horizontal wells where fresh water is taken as the drilling fluid.
文摘It is of great significance to study the controlling effect of sealing systems on CBM enrichment in coalbed methane (CBM) exploration anddevelopment. In this paper, the relationships between CBM enrichment and geological elements were analyzed. The geological elements includesealing layers (e.g. regional cap rock, regional floor, and immediate roof and floor), later structural adjustment and strata production status. It isshown that CBM tends to enrich in the areas where regional mudstone cap rocks and floors are distributed stably, structures are uplifted andinversed slightly after the hydrocarbon accumulation period and the strata is gentle in a balanced state. Then, the concept of sealing system wasput forward based on the worldwide CBM exploration and development practices over the years. A sealing system refers to a geological unitcomposed of a lateral stable zone and cap rock which prevents gas from migrating upward and downward. In a sealing system, CBM can getenriched and coal-measure gas can also be accumulated. Finally, three gas reservoir types (i.e., sandwich-type CBM reservoir, associated CBM-sandstone gas reservoir and coal-derived sandstone gas reservoir) were identified based on the configuration relationships between elements ofthe CBM (or coal-measure gas) sealing system. It is recommended to change the exploration ideas from simple CBM exploration to 3D CBMand coal-measure gas exploration. In addition, an evaluation index system of CBM (or coal-measure gas) geological selection was established. Itis pointed out that good application effects may be realized if the stereoscopic CBM and coal-measure gas exploration is applied in the JunggarBasin and the eastern margin of the Ordos Basin.
