The permeability contrast between the Hot Dry Rock(HDR)reservoir and the surrounding formations is a key factor governing fluid loss in Enhanced Geothermal Systems(EGS).This study thus aims to investigate its impact o...The permeability contrast between the Hot Dry Rock(HDR)reservoir and the surrounding formations is a key factor governing fluid loss in Enhanced Geothermal Systems(EGS).This study thus aims to investigate its impact on system performance under varying operating conditions,and a three-dimensional thermo–hydro–mechanical(THM)coupled EGS model is developed based on the geological parameters of the GR1 well in the Qiabuqia region.The coupled processes of fluid flow,heat transfer,and geomechanics within the reservoir under varying reservoir–surrounding rock permeability contrasts,as well as the flow and heat exchange along the wellbores fromthe reservoir to the surface are simulated.Then,the influence of permeability contrast,production pressure,injection rate,and injection temperature on fluid loss and heat extraction performance over a 35-year operation period is quantitatively assessed.Theresults show that increasing the permeability contrast effectively suppresses fluid loss and enhances early-stage heat production,but also accelerates thermal breakthrough and shortens the stable operation period.When the contrast rises from 1×10^(3) to 1×10^(5),the cumulative fluid loss rate drops from 54.34%to 0.23%,and the total heat production increases by 132%,although the breakthrough occurs 5 years earlier.Meanwhile,higher production pressure delays thermal breakthrough and slows transient temperature decline,but exacerbates fluid loss and reduces heat production power.For instance,raising the pressure from 17 to 21 MPa increases the fluid loss rate from 33.17%to 54.34%and reduces average annual heat production power from 25.43 to 14.59MWth.In addition,increasing the injection rate(46 to 66 kg/s)lowers fluid loss rate but brings forward thermal breakthrough by 9 years and causes a 41 K temperature drop at the end of operation.Notably,under high fluid loss,the dynamic response pattern of heat production power shifts from a temperature-dominated“stable–breakthrough–decline”mode to a novel“rising–breakthrough–decline”mode jointly governed by both production temperature and flow rates.These findings provide theoretical support and engineering guidance for improving EGS performance.展开更多
During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtr...During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.展开更多
Cementing in deep and ultra-deep reservoirs often faces the critical challenge of additive degradation in high-temperature environments.Addressing this,1-vinylimidazole(VM)was incorporated into the copolymerization of...Cementing in deep and ultra-deep reservoirs often faces the critical challenge of additive degradation in high-temperature environments.Addressing this,1-vinylimidazole(VM)was incorporated into the copolymerization of N,N-dimethylacrylamide,itaconic acid,and 2-acrylamido-2-methylpropanesulfonic acid to synthesize a tetrapolymer(PDVI).Using aqueous free radical polymerization optimized by response surface methodology,the resulting PDVI exhibited superior fluid loss reduction in hightemperature and high-salinity conditions.Compared to the control sample PDI,PDVI reduced fluid loss from 64.7 mL to 25 mL at 200℃ and from 105.7 mL to 42.5 mL at 240℃,while maintaining filtration below 70 mL in 20%NaCl.Structural characterization via ^(1)H NMR and FTIR,combined with TGA and aging tests,confirmed that VM's rigid five-membered ring significantly enhanced thermal stability;molecular weight retention after aging at 220℃ increased from 46.13%to 68.31%.Furthermore,DLS,SEM,and zeta potential analyses indicated that VM's cationic nature facilitates robust polymer adsorption on cement particles.This mechanism ensures effective particle dispersion and the formation of a dense filter cake even under extreme conditions.These findings provide essential insights for developing high-performance polymeric additives for cementing in complex downhole environments.展开更多
Two types of ultra-high-temperature resistant water-based drilling fluid additives were designed and developed:an ultra-high-temperature resistant salt-tolerant polymer fluid loss reducer,and an ultra-high-temperature...Two types of ultra-high-temperature resistant water-based drilling fluid additives were designed and developed:an ultra-high-temperature resistant salt-tolerant polymer fluid loss reducer,and an ultra-high-temperature resistant micro-nano plugging agent.An ultra-high-temperature resistant water-based drilling fluid system meeting the requirements of ultra-deep well drilling was established.Laboratory test and field application were employed for performance evaluation.The ultra-high-temperature and high-salt resistant polymer fluid loss reducer exhibits a mesh-like membrane structure with numerous cross-linking points,and its high-temperature and high-pressure(HTHP)loss was 28.2 m L after aging at 220℃under saturated salt conditions.The ultra-high-temperature resistant micro-nano plugging agent adaptively filled mud cake pores/fractures through deformation,thus reducing the fluid loss.At elevated temperatures,it transitioned to a viscoelastic state to effectively cement the rock on wellbore wall and enhanced wall stability.The ultra-high-temperature resistant water-based drilling fluid system with a density of 1.6 g/cm^(3)exhibits excellent rheological properties at high temperature and high pressure.Its HTHP fluid loss at 220℃was only 9.6 m L.It maintains a stable performance under high-temperature and high-salt conditions,with a sedimentation factor below 0.52 after holding at high temperature for 7 d,and generates no H_(2)S gas after aging,demonstrating good lubricity and safety.This drilling fluid system has been successfully applied in the 10000-meter ultra-deep well of China,Shenditake 1,in Tarim Oilfield,ensuring the well's successful drilling to a depth of 10910 m.展开更多
Wellbore instability is an issue that,if left untreated,can cause wells to collapse,resulting in human,environmental,equipment,and revenue losses.Drilling fluids have been used to enhance the drilling process by lubri...Wellbore instability is an issue that,if left untreated,can cause wells to collapse,resulting in human,environmental,equipment,and revenue losses.Drilling fluids have been used to enhance the drilling process by lubricating and cooling the drill bit,eliminating cuttings,and most importantly,by improving the stability of the well by preventing fluid loss.However,there has been an increase in operational demands and challenges that call for drilling fluids to be more effective,economical,sustainable,and environmentally friendly.With shales that have infinitesimally small pores,nanoparticle additives in drilling fluids can be crucial in providing the properties that are necessary to prevent fluid loss and provide wellbore stability while meeting the operational demands of the present day.Therefore,this paper examines the use of nanoparticle additives including copper(Ⅱ)oxide(CuO),magnesium oxide(MgO),and aluminum oxide(Al_(2)O_(3))where they are tested under three conditions using the permeable plugging tester(PPT),high-temperature high-pressure(HTHP)fluid loss apparatus,and API low-temperature e low-pressure(LTLP)fluid loss apparatus under concentrations of 0.03%and 0.10%.Finally,based on the results,each nanoparticle sample(particle sizes between one and 100 nm)performed well in contributing to the aim of this project.CuO is the most effective inhibitor across all concentrations and under the three different conditions.It contributed to reducing the fluid loss from 37.6 mL to 18.2 and 13.2 mL,which is between 52%and 65%of fluid reduction.For MgO,it contributed to fluid loss reduction to 23.8 mL and 15 mL,which translated to 37%e60%of fluid loss reduction.The use of Al_(2)O_(3) nanoparticles resulted in a fluid loss reduction to 33.6 mL and 17.8 mL,reducing the fluid loss up to 11%,at HTHP and up to 53%at LTLP.Unlike CuO and MgO,Al_(2)O_(3) was less effective under HTHP conditions when compared to LTLP conditions.Al_(2)O_(3) did not suffer as a significant diminishing benefit with increasing concentration in LTLP conditions however which means that at a higher concentration,it may begin to be more effective.Each material used in this study has its own specific and technical characteristics that will help create a progressive amount of property,such as providing stability and withstanding the high-temperature and highpressure condition downhole.展开更多
The pressure loss of cross-flow perforated of physical modeling, simulation and data processing. muffler has been computed with the procedure Three-dimensional computational fluid dynamics （CFD） has been used to inv...The pressure loss of cross-flow perforated of physical modeling, simulation and data processing. muffler has been computed with the procedure Three-dimensional computational fluid dynamics （CFD） has been used to investigate the relations of porosities, flow velocity and diameter of the holes with the pressure loss. Accordingly, some preliminary results have been obtained that pressure loss increases with porosity descent as nearly a hyperbolic trend, rising flow velocity of the input makes the pressure loss increasing with parabola trend, diameter of holes affects little about pressure loss of the muffler. Otherwise, the holes on the perforated pipes make the air flow gently and meanly, which decreases the air impact to the wall and pipes in the muffler. A practical perforated muffler is used to illustrate the available of this method for pressure loss computation, and the comparison shows that the computation results with the method of CFD has reference value for muffler design.展开更多
CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their st...CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their structural and optical properties using X-ray powder diffraction(XRD)patterns,Fourier transform infrared spectroscopy,Raman spectroscopy,UV–Visible and photoluminescence studies.Morphological and compositional studies were carried out using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy,while the magnetic properties were determined using alternating gradient magnetometer and Mossbauer to define the magneto-structural effects of shell formation on the core NPs.Induction heating properties of CoFe2O4 and CoFe2O4@Au CS magnetic nanoparticles(MNPs)have been investigated and correlated with magneto-structural properties.Specific absorption rate and intrinsic loss power were calculated for these MNPs within the human tolerable range of frequency and amplitude,suggesting their potential in magnetic fluid hyperthermia therapy for possible cancer treatment.展开更多
Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling...Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling, and serious pollution of drilling environment with oil-based drilling fluid, a water-based drilling fluid system for anti-collapse and anti-leakage was studied. A water-based drilling fluid system with anti-collapse and anti-leakage was formed by introducing functional treatment agents, such as polypolysaccharide MEG, polymer emulsion film forming wall cementing agent LFGB, polyamine inhibitor LCFA and deformable particle plugging agent BXLZ, into the conventional water-based drilling fluid. After rolling at 130°C for 16 h, the system has good rheological properties, low filtration loss, good inhibition, lubrication and plugging properties. It has good plugging properties for 0.12 mm, 0.24 mm, 0.38 mm micro-cracks and 400 mD and 800 mD sand plates. The system was successfully tested on site in August 2019 in Fuling Reef Block, showing good rheological properties, solid wall plugging, and strong ability to seal and inhibit fracture expansion. There was no block falling in the drilling process, and the tripping, casing running and well cementing operations were all smooth, which provided a new technical idea and scheme for environmental protection and green drilling in Fuling shale gas exploitation.展开更多
基金supported by the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZC20251944)the National Natural Science Foundation of China(No.52376044)the National Key Research and Development Program of China(2024YFE0100800).
文摘The permeability contrast between the Hot Dry Rock(HDR)reservoir and the surrounding formations is a key factor governing fluid loss in Enhanced Geothermal Systems(EGS).This study thus aims to investigate its impact on system performance under varying operating conditions,and a three-dimensional thermo–hydro–mechanical(THM)coupled EGS model is developed based on the geological parameters of the GR1 well in the Qiabuqia region.The coupled processes of fluid flow,heat transfer,and geomechanics within the reservoir under varying reservoir–surrounding rock permeability contrasts,as well as the flow and heat exchange along the wellbores fromthe reservoir to the surface are simulated.Then,the influence of permeability contrast,production pressure,injection rate,and injection temperature on fluid loss and heat extraction performance over a 35-year operation period is quantitatively assessed.Theresults show that increasing the permeability contrast effectively suppresses fluid loss and enhances early-stage heat production,but also accelerates thermal breakthrough and shortens the stable operation period.When the contrast rises from 1×10^(3) to 1×10^(5),the cumulative fluid loss rate drops from 54.34%to 0.23%,and the total heat production increases by 132%,although the breakthrough occurs 5 years earlier.Meanwhile,higher production pressure delays thermal breakthrough and slows transient temperature decline,but exacerbates fluid loss and reduces heat production power.For instance,raising the pressure from 17 to 21 MPa increases the fluid loss rate from 33.17%to 54.34%and reduces average annual heat production power from 25.43 to 14.59MWth.In addition,increasing the injection rate(46 to 66 kg/s)lowers fluid loss rate but brings forward thermal breakthrough by 9 years and causes a 41 K temperature drop at the end of operation.Notably,under high fluid loss,the dynamic response pattern of heat production power shifts from a temperature-dominated“stable–breakthrough–decline”mode to a novel“rising–breakthrough–decline”mode jointly governed by both production temperature and flow rates.These findings provide theoretical support and engineering guidance for improving EGS performance.
基金the National Natural Science Foundation of China(No.52204023)China Postdoctoral Science Foundation(2022M713465)Postdoctoral Innovation Talent Support of Shandong Province(SDBX2022033)。
文摘During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.
基金supported by Project of Basic Science Center of National Natural Science Foundation(No.52288101)the Fundamental Research Funds for the Central Universities(23CX05001A).
文摘Cementing in deep and ultra-deep reservoirs often faces the critical challenge of additive degradation in high-temperature environments.Addressing this,1-vinylimidazole(VM)was incorporated into the copolymerization of N,N-dimethylacrylamide,itaconic acid,and 2-acrylamido-2-methylpropanesulfonic acid to synthesize a tetrapolymer(PDVI).Using aqueous free radical polymerization optimized by response surface methodology,the resulting PDVI exhibited superior fluid loss reduction in hightemperature and high-salinity conditions.Compared to the control sample PDI,PDVI reduced fluid loss from 64.7 mL to 25 mL at 200℃ and from 105.7 mL to 42.5 mL at 240℃,while maintaining filtration below 70 mL in 20%NaCl.Structural characterization via ^(1)H NMR and FTIR,combined with TGA and aging tests,confirmed that VM's rigid five-membered ring significantly enhanced thermal stability;molecular weight retention after aging at 220℃ increased from 46.13%to 68.31%.Furthermore,DLS,SEM,and zeta potential analyses indicated that VM's cationic nature facilitates robust polymer adsorption on cement particles.This mechanism ensures effective particle dispersion and the formation of a dense filter cake even under extreme conditions.These findings provide essential insights for developing high-performance polymeric additives for cementing in complex downhole environments.
基金Supported by the CNPC Science and Technology Project(2022ZG06)Xinjiang Uygur Autonomous Region Science and Technology Innovation Talent Project(2024TSYCCX0061)。
文摘Two types of ultra-high-temperature resistant water-based drilling fluid additives were designed and developed:an ultra-high-temperature resistant salt-tolerant polymer fluid loss reducer,and an ultra-high-temperature resistant micro-nano plugging agent.An ultra-high-temperature resistant water-based drilling fluid system meeting the requirements of ultra-deep well drilling was established.Laboratory test and field application were employed for performance evaluation.The ultra-high-temperature and high-salt resistant polymer fluid loss reducer exhibits a mesh-like membrane structure with numerous cross-linking points,and its high-temperature and high-pressure(HTHP)loss was 28.2 m L after aging at 220℃under saturated salt conditions.The ultra-high-temperature resistant micro-nano plugging agent adaptively filled mud cake pores/fractures through deformation,thus reducing the fluid loss.At elevated temperatures,it transitioned to a viscoelastic state to effectively cement the rock on wellbore wall and enhanced wall stability.The ultra-high-temperature resistant water-based drilling fluid system with a density of 1.6 g/cm^(3)exhibits excellent rheological properties at high temperature and high pressure.Its HTHP fluid loss at 220℃was only 9.6 m L.It maintains a stable performance under high-temperature and high-salt conditions,with a sedimentation factor below 0.52 after holding at high temperature for 7 d,and generates no H_(2)S gas after aging,demonstrating good lubricity and safety.This drilling fluid system has been successfully applied in the 10000-meter ultra-deep well of China,Shenditake 1,in Tarim Oilfield,ensuring the well's successful drilling to a depth of 10910 m.
文摘Wellbore instability is an issue that,if left untreated,can cause wells to collapse,resulting in human,environmental,equipment,and revenue losses.Drilling fluids have been used to enhance the drilling process by lubricating and cooling the drill bit,eliminating cuttings,and most importantly,by improving the stability of the well by preventing fluid loss.However,there has been an increase in operational demands and challenges that call for drilling fluids to be more effective,economical,sustainable,and environmentally friendly.With shales that have infinitesimally small pores,nanoparticle additives in drilling fluids can be crucial in providing the properties that are necessary to prevent fluid loss and provide wellbore stability while meeting the operational demands of the present day.Therefore,this paper examines the use of nanoparticle additives including copper(Ⅱ)oxide(CuO),magnesium oxide(MgO),and aluminum oxide(Al_(2)O_(3))where they are tested under three conditions using the permeable plugging tester(PPT),high-temperature high-pressure(HTHP)fluid loss apparatus,and API low-temperature e low-pressure(LTLP)fluid loss apparatus under concentrations of 0.03%and 0.10%.Finally,based on the results,each nanoparticle sample(particle sizes between one and 100 nm)performed well in contributing to the aim of this project.CuO is the most effective inhibitor across all concentrations and under the three different conditions.It contributed to reducing the fluid loss from 37.6 mL to 18.2 and 13.2 mL,which is between 52%and 65%of fluid reduction.For MgO,it contributed to fluid loss reduction to 23.8 mL and 15 mL,which translated to 37%e60%of fluid loss reduction.The use of Al_(2)O_(3) nanoparticles resulted in a fluid loss reduction to 33.6 mL and 17.8 mL,reducing the fluid loss up to 11%,at HTHP and up to 53%at LTLP.Unlike CuO and MgO,Al_(2)O_(3) was less effective under HTHP conditions when compared to LTLP conditions.Al_(2)O_(3) did not suffer as a significant diminishing benefit with increasing concentration in LTLP conditions however which means that at a higher concentration,it may begin to be more effective.Each material used in this study has its own specific and technical characteristics that will help create a progressive amount of property,such as providing stability and withstanding the high-temperature and highpressure condition downhole.
文摘The pressure loss of cross-flow perforated of physical modeling, simulation and data processing. muffler has been computed with the procedure Three-dimensional computational fluid dynamics （CFD） has been used to investigate the relations of porosities, flow velocity and diameter of the holes with the pressure loss. Accordingly, some preliminary results have been obtained that pressure loss increases with porosity descent as nearly a hyperbolic trend, rising flow velocity of the input makes the pressure loss increasing with parabola trend, diameter of holes affects little about pressure loss of the muffler. Otherwise, the holes on the perforated pipes make the air flow gently and meanly, which decreases the air impact to the wall and pipes in the muffler. A practical perforated muffler is used to illustrate the available of this method for pressure loss computation, and the comparison shows that the computation results with the method of CFD has reference value for muffler design.
基金Author (Sandip Sabale) is thankful to University Grants Commission, New Delhi, India, for Raman Fellowship to work in USA (F. No. 5-105/2016 (IC), February 10, 2016
文摘CoFe2O4 nanoparticles(NPs)and surface modified with gold(Au)have been synthesized by a thermal decomposition method.The obtained NPs and formation of CoFe2O4@Au core–shell(CS)were confirmed by characterizing their structural and optical properties using X-ray powder diffraction(XRD)patterns,Fourier transform infrared spectroscopy,Raman spectroscopy,UV–Visible and photoluminescence studies.Morphological and compositional studies were carried out using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy,while the magnetic properties were determined using alternating gradient magnetometer and Mossbauer to define the magneto-structural effects of shell formation on the core NPs.Induction heating properties of CoFe2O4 and CoFe2O4@Au CS magnetic nanoparticles(MNPs)have been investigated and correlated with magneto-structural properties.Specific absorption rate and intrinsic loss power were calculated for these MNPs within the human tolerable range of frequency and amplitude,suggesting their potential in magnetic fluid hyperthermia therapy for possible cancer treatment.
文摘Aiming at the problems of microfracture development in hard brittle shale gas layer in Fuling block, Chongqing, such as collapse of borehole wall and the existence of permeability loss of microfracture during drilling, and serious pollution of drilling environment with oil-based drilling fluid, a water-based drilling fluid system for anti-collapse and anti-leakage was studied. A water-based drilling fluid system with anti-collapse and anti-leakage was formed by introducing functional treatment agents, such as polypolysaccharide MEG, polymer emulsion film forming wall cementing agent LFGB, polyamine inhibitor LCFA and deformable particle plugging agent BXLZ, into the conventional water-based drilling fluid. After rolling at 130°C for 16 h, the system has good rheological properties, low filtration loss, good inhibition, lubrication and plugging properties. It has good plugging properties for 0.12 mm, 0.24 mm, 0.38 mm micro-cracks and 400 mD and 800 mD sand plates. The system was successfully tested on site in August 2019 in Fuling Reef Block, showing good rheological properties, solid wall plugging, and strong ability to seal and inhibit fracture expansion. There was no block falling in the drilling process, and the tripping, casing running and well cementing operations were all smooth, which provided a new technical idea and scheme for environmental protection and green drilling in Fuling shale gas exploitation.
