This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pr...This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pressure relief of the lower section coal after the upper section working face is mined. It theoretically analyzed the reasonable layout of the drainage boreholes, and designed the drainage borehole layout accordingly. In the upper and lower section of the working face, the actual drainage effect of the boreholes was inspected, and the air exhaust gas volume in the working face was statistically analyzed. It was confirmed that the layout of boreholes was reasonable, the gas control effect of working face was greatly improved and fully met the needs of safe mining. The control effect was greatly improved and the need for safe mining was fully met, and thus a gas drainage technology suitable for the coal seam storage conditions and mining technology of the Adaohai Coal Mine was found. That is to say: the gas emission from the working face of the section mining mainly comes from its lower coal body. Pre-draining the lower coal body of the section and depressurizing gas interception and drainage are the key to effectively solve the problem of gas emission from the working face. Drainage boreholes in the working face of the section should be arranged at high and low positions. The high-level boreholes are located about 2 m from the top of the working face, and the high-level boreholes are about 9 m away from the top of the working face. Through the pre drainage of high and low-level boreholes in advance and the interception and pressure relief drainage, the gas control in the horizontal sublevel fully mechanized caving mining face in steep and extra thick coal seam can realize a virtuous cycle.展开更多
The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced do...The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced down-hole working conditions(high-temperature,high-pressure,and solid-phase-dominance)directly impact the stability of the wellbore wall.Focusing on the impact of bottom-hole osmotic pressure and solid phase content and a series of density-reductionfield tests,we identified suitable countermeasures.In this paper,we discuss the impact of high osmotic pressure and operational measures,and provide details of thefield tests,which indicate that maintaining a higher osmotic pressure at the bottom-hole can reduce the formation pore pressure of the bottom-hole,widen thefluid density window,and maintain the stability of the wellbore wall.By improving the HDOF formula,such as using new treatment agents(e.g.,polymer-modified nano-sealing agent and ultra-micro barite weight additive)and optimizing the solid particle size distribution of HDOF,we can effectively address the down-hole problems.Thefield test of“pressure-controlled drillingþdensity reduction”in horizontal drilling operations was found to reduce the complexity of down-hole faults,improve the rate of penetration,and reduce overall costs.展开更多
Segmental perforation is widely used for horizontal wells. However,the flow of fluid in porous media is a complex problem. Using the Fourier transform,principle of potential superposition,trigonometric function transf...Segmental perforation is widely used for horizontal wells. However,the flow of fluid in porous media is a complex problem. Using the Fourier transform,principle of potential superposition,trigonometric function transform,asymptotic analyses,a pressure solution of a pseudo steady-state flow model in 3D circular-boxed media has been established. Comparing with the productivity of vertical wells,an equivalence radius model can be obtained. Based on the model,a method of evaluating the productivity of segmental perforation horizontal well is presented by means of principle of superposition. It shows that the equivalence radius is different for various positions of horizontal wells; the output of both ends of horizontal wells is greater than the others under the same length of perforation interval; it is more important to obtain high productivity by increasing the length of perforation interval than enlarging the spacing between perforation intervals. The result of this research can be used to ascertain the yield of each perforated interval.展开更多
We present results from one of a set of studies run in the early 2000＇s, which looked at weak signals in terms of what consumers wanted. That study, on milk, revealed four distinct mind-sets, groups of respondents wh...We present results from one of a set of studies run in the early 2000＇s, which looked at weak signals in terms of what consumers wanted. That study, on milk, revealed four distinct mind-sets, groups of respondents who thought alike. These are： S1 Traditional ＋ Health, S2 Traditional ＋ Healthful Ingredients, $3 Traditional ＋ Indulgent, S4 Listens to Authority, respectively. At that time the focus on foods as the source of health and wellness was just beginning. We show how to discover hitherto new, unexpected mind-sets of respondents, using experimental design of messaging, coupled with deconstruction of these messages by regression, and followed by clustering. We suggest that this approach to messaging consumers using experimental design provides a powerful method to uncover emerging mind-sets in the consumer population.展开更多
Coiled tubing drilling and grinding technology is widely used in shale gas well exploitation projects in Sichuan-Chongqing area. In recent years, the exploration and development of unconventional oil and gas resources...Coiled tubing drilling and grinding technology is widely used in shale gas well exploitation projects in Sichuan-Chongqing area. In recent years, the exploration and development of unconventional oil and gas resources such as shale gas and shale oil have developed rapidly in China, and shale gas in Sichuan-Chongqing block has gradually developed in the direction of deep layer, normal pressure and encryption adjustment in old areas. Affected by casing deformation, high temperature in the well, high pressure in the well, tool performance, operating parameters and other factors, the coiled tubing is prone to sticking due to the unreturned debris, and the complicated horizontal section of the well trajectory leads to the tubing self-locking not reaching the target position, and the friction resistance between tubing and casing leads to serious tool wear or fracture, which has a serious impact on the subsequent exploitation of shale gas wells. In this paper, various risks in drilling and grinding bridge plug technology during fracturing are analyzed, and according to the actual situation on the spot, some methods are put forward, such as shoe grinding selection scheme, tool selection optimization and auxiliary material use, drilling and grinding technical parameters optimization, etc., in order to avoid complicated situations and achieve the purpose of improving quality and increasing efficiency.展开更多
文摘This paper analyzes the gas source of the horizontally sectioned fully mechanized caving face in the steeply inclined and extra-thick seam of Adaohai Coal Mine, and numerically simulates the stress distribution and pressure relief of the lower section coal after the upper section working face is mined. It theoretically analyzed the reasonable layout of the drainage boreholes, and designed the drainage borehole layout accordingly. In the upper and lower section of the working face, the actual drainage effect of the boreholes was inspected, and the air exhaust gas volume in the working face was statistically analyzed. It was confirmed that the layout of boreholes was reasonable, the gas control effect of working face was greatly improved and fully met the needs of safe mining. The control effect was greatly improved and the need for safe mining was fully met, and thus a gas drainage technology suitable for the coal seam storage conditions and mining technology of the Adaohai Coal Mine was found. That is to say: the gas emission from the working face of the section mining mainly comes from its lower coal body. Pre-draining the lower coal body of the section and depressurizing gas interception and drainage are the key to effectively solve the problem of gas emission from the working face. Drainage boreholes in the working face of the section should be arranged at high and low positions. The high-level boreholes are located about 2 m from the top of the working face, and the high-level boreholes are about 9 m away from the top of the working face. Through the pre drainage of high and low-level boreholes in advance and the interception and pressure relief drainage, the gas control in the horizontal sublevel fully mechanized caving mining face in steep and extra thick coal seam can realize a virtuous cycle.
基金supported by the National Science and Technology Program during the Thirteenth Five-year Plan Period(CN).
文摘The operational experience of a horizontal segment well within the hard brittle shale layer of Longmaxi Formation in the southern Sichuan area demonstrates that the high-density oil-based drillingfluid(HDOF)induced down-hole working conditions(high-temperature,high-pressure,and solid-phase-dominance)directly impact the stability of the wellbore wall.Focusing on the impact of bottom-hole osmotic pressure and solid phase content and a series of density-reductionfield tests,we identified suitable countermeasures.In this paper,we discuss the impact of high osmotic pressure and operational measures,and provide details of thefield tests,which indicate that maintaining a higher osmotic pressure at the bottom-hole can reduce the formation pore pressure of the bottom-hole,widen thefluid density window,and maintain the stability of the wellbore wall.By improving the HDOF formula,such as using new treatment agents(e.g.,polymer-modified nano-sealing agent and ultra-micro barite weight additive)and optimizing the solid particle size distribution of HDOF,we can effectively address the down-hole problems.Thefield test of“pressure-controlled drillingþdensity reduction”in horizontal drilling operations was found to reduce the complexity of down-hole faults,improve the rate of penetration,and reduce overall costs.
基金supported by the China National 973 Program (Grant No. 2003CB214602)
文摘Segmental perforation is widely used for horizontal wells. However,the flow of fluid in porous media is a complex problem. Using the Fourier transform,principle of potential superposition,trigonometric function transform,asymptotic analyses,a pressure solution of a pseudo steady-state flow model in 3D circular-boxed media has been established. Comparing with the productivity of vertical wells,an equivalence radius model can be obtained. Based on the model,a method of evaluating the productivity of segmental perforation horizontal well is presented by means of principle of superposition. It shows that the equivalence radius is different for various positions of horizontal wells; the output of both ends of horizontal wells is greater than the others under the same length of perforation interval; it is more important to obtain high productivity by increasing the length of perforation interval than enlarging the spacing between perforation intervals. The result of this research can be used to ascertain the yield of each perforated interval.
文摘We present results from one of a set of studies run in the early 2000＇s, which looked at weak signals in terms of what consumers wanted. That study, on milk, revealed four distinct mind-sets, groups of respondents who thought alike. These are： S1 Traditional ＋ Health, S2 Traditional ＋ Healthful Ingredients, $3 Traditional ＋ Indulgent, S4 Listens to Authority, respectively. At that time the focus on foods as the source of health and wellness was just beginning. We show how to discover hitherto new, unexpected mind-sets of respondents, using experimental design of messaging, coupled with deconstruction of these messages by regression, and followed by clustering. We suggest that this approach to messaging consumers using experimental design provides a powerful method to uncover emerging mind-sets in the consumer population.
文摘Coiled tubing drilling and grinding technology is widely used in shale gas well exploitation projects in Sichuan-Chongqing area. In recent years, the exploration and development of unconventional oil and gas resources such as shale gas and shale oil have developed rapidly in China, and shale gas in Sichuan-Chongqing block has gradually developed in the direction of deep layer, normal pressure and encryption adjustment in old areas. Affected by casing deformation, high temperature in the well, high pressure in the well, tool performance, operating parameters and other factors, the coiled tubing is prone to sticking due to the unreturned debris, and the complicated horizontal section of the well trajectory leads to the tubing self-locking not reaching the target position, and the friction resistance between tubing and casing leads to serious tool wear or fracture, which has a serious impact on the subsequent exploitation of shale gas wells. In this paper, various risks in drilling and grinding bridge plug technology during fracturing are analyzed, and according to the actual situation on the spot, some methods are put forward, such as shoe grinding selection scheme, tool selection optimization and auxiliary material use, drilling and grinding technical parameters optimization, etc., in order to avoid complicated situations and achieve the purpose of improving quality and increasing efficiency.
