The ash mudstone in some oil formations is highly water-sensitive.The oil formation is fractured,and the risk of well leakage and collapse is not negligible.This study presents a countermeasure for well collapse preve...The ash mudstone in some oil formations is highly water-sensitive.The oil formation is fractured,and the risk of well leakage and collapse is not negligible.This study presents a countermeasure for well collapse prevention,based on a“force-chemistry synergistic balance”approach and the utilization of environmentally friendly and efficient hydration inhibitors.The relevance of this approach is demonstrated considering a drilling fluid system with the high potassium content.The analysis shows that the system can maintain good rheological properties,filtration loss and suspension stability even after aging at 130℃ for 16 h.The primary roll recovery of rock chips is better than 98%.The secondary rolling recovery rate is 89%.The rapid water loss is close to zero.The effects of carrying rock,sand,hydration inhibition and dispersion of drill chips are all noticeable.展开更多
Based on an analysis of the fractal structures and mass transport mechanism of typical shear-fluid-ore formation system, the fractal dispersion theory of the fluid system was used in the dynamic study of the ore forma...Based on an analysis of the fractal structures and mass transport mechanism of typical shear-fluid-ore formation system, the fractal dispersion theory of the fluid system was used in the dynamic study of the ore formation system. The model of point-source diffusive illuviation of the shear-fluid-ore formation system was constructed, and the numerical simulation of dynamics of the ore formation system was finished. The result shows that: (1) The metallogenic system have nested fractal structure. Different fractal dimension values in different systems show unbalance and inhomogeneity of ore-forming processes in the geohistory. It is an important parameter to symbolize the process of remobilization and accumulation of ore-forming materials. Also it can indicate the dynamics of the metallogenic system quantitatively to some extent. (2) In essence, the fractal dispersive ore-forming dynamics is a combination of multi-processes dominated by fluid dynamics and supplemented by molecule dispersion in fluids and fluid-rock interaction. It changes components and physico-chemical properties of primary rocks and fluids, favouring deposition and mineralization of ore-forming materials. (3) Gold ore-forming processes in different types of shear zones are quite different. (1) In a metallogenic system with inhomogeneous volumetric change and inhomogeneous shear, mineralization occurs in structural barriers in the centre of a shear zone and in geochemical barriers in the shear zone near its boundaries. But there is little possibility of mineralization out of the shear zone. (2) As to a metallogenic system with inhomogeneous volumetric change and simple shear, mineralization may occur only in structural barriers near the centre of the shear zone. (3) In a metallogenic system with homogeneous volumetric change and inhomogeneous shear, mineralization may occur in geochemical barriers both within and out of the shear zone.展开更多
Fracturing fluid is the blood of fracturing construction, which is very important for fracturing, which requires that fracturing fluid needs to have good performance. The three commonly used fracturing fluids for unco...Fracturing fluid is the blood of fracturing construction, which is very important for fracturing, which requires that fracturing fluid needs to have good performance. The three commonly used fracturing fluids for unconventional oil and gas reservoir transformation are: 1) Guar gum fracturing fluid;2) Water-based emulsion slippery water fracturing fluid;3) Oil-based emulsion slippery water fracturing fluid. In this paper, water samples and other experimental data provided by Mahu Oilfield are used to evaluate three different fracturing fluid systems in laboratory. The formulas of the three different fracturing fluid systems are: 1) Water-based emulsion slippery water fracturing fluid is clean slippery water fracturing fluid 0.1% JHFR-2D drag reducer + 0.2% JHFD-2 multifunctional additive;2) Oil-based emulsion slippery water fracturing fluid 0.1% A agent + 0.2% B agent;3) Guar gum fracturing fluid 0.1% guanidine gum + 0.5% drainage aid + 0.3% demulsifier. The compatibility, drag reduction performance, reservoir damage, residue content, anti-swelling performance, surface interfacial tension, viscosity and other properties of three different slippery water fracturing fluid systems were studied. Through laboratory experiments, the comprehensive indicators show that clean slippery water fracturing fluid has obvious advantages.展开更多
Based on detailed and systematic researches of the geology of ore deposits, fluid inclusions and isotope geochemistry etc., and regarding the Late Paleozoic fluid system of the Yuebei Basin as an integrated object in ...Based on detailed and systematic researches of the geology of ore deposits, fluid inclusions and isotope geochemistry etc., and regarding the Late Paleozoic fluid system of the Yuebei Basin as an integrated object in this paper, we have revealed the temporo-spatial evolution law of the basin’s fluid system and discussed its ore-forming effects by simulating and analyzing the distribution of ore-forming elements, the fluid thermodynamics and dynamics of evolution processes of this basin. The results show that Late Paleozoic ore-forming fluid systems of the Yuebei Basin include four basic types as follows. (1) The sea floor volcanic-exhalation system developed during the rapid basin slip-extension stage in the Mid-Late Devonian, which affected the Dabaoshan region. It thus formed the Dabaoshan-type Cu-Pb-Zn-Fe sea floor volcanic-exhalation sedimentary deposits. (2) The compaction fluid system developed during the stable spreading and thermal subsidence-compression stage of the basin in the Mid-Late Devonian. The range of its effects extended all over the whole basin. It resulted in filling-metasomatic deposits, such as the Hongyan-type pyrite deposits and pyrite sheet within the Fankou-type Cu-Pb-Zn-S deposits. (3) The hot water circulation system of sea floor developed during the stage of basin uplifting and micro-aulacogen from the late Late Carboniferous to Middle Carboniferous. The range of its effects covered the Fankou region. It thus formed MVT deposits, such as the main orebody of the Fankou-type Pb-Zn-S deposits. (4) The gravity fluid system developed during the stage of fold uplifting and the basin closed from Middle Triassic to Jurassic, forming groundwater hydrothermal deposits, e.g. the veinlet Pb-Zn-calcite orebodies of the Fankou-type Pb-Zn-S deposits. Migration and concentration of the ore-forming fluids were constrained by the state of temporo-spatial distribution of its fluid potential. Growth faults not only converged the fluids and drove them to move upwards, but also the fluids often crossed the faults to the edges of the basin at the bottom of these faults and the lithologic interfaces, and even migrated to the basin’s edges from top to bottom along the faults, which may be one of the basic reasons for the stratabound deposits to cluster mainly along the contemporaneous faults on the inner border of the basin. The superposed mineralization resulting from the multi-stage activity of contemporaneous faults and ore-forming fluid systems in the basin may be one of the key factors for forming superlarge ore deposits.展开更多
A quite general coupled variable coefficient modified KdV (VCmKdV) equation in a two-layer fluid systemis derived by means of the reductive perturbation method.Making use of the CK's direct method,some similarityr...A quite general coupled variable coefficient modified KdV (VCmKdV) equation in a two-layer fluid systemis derived by means of the reductive perturbation method.Making use of the CK's direct method,some similarityreductions of the coupled VCmKdV equation are obtained and their corresponding group explanations are discussed.Some exact solutions of the coupled equations are also presented.展开更多
Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon...Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon reservoir. Due to the solid free system, the damage of solid phase particles on reservoir, especially low permeability oil and gas layer, can be greatly eliminated, at the same time, drilling fluid and completion fluid have greater compatibility. It will avoid that precipitation which is not compatible with drilling and completion fluid and generates damages on reservoir. And because mud cake of the solid free system is thin and resilient, it is conductive to improve cementing quality greatly. Experiments show that the formate drilling and completion system has good rheological property, strong inhibition ability, good lubricating performance, good compatibility with reservoir rocks and formation water at high temperature.展开更多
Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional met...Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore-forming fluid systems are classified in this article. It is proposed that the fluid ore-forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crustmantle interaction and magmatic-tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore-forming systems and geological backgrounds.展开更多
In this article, we study the electromagnetic fluid system in three-dimensional whole space R^3. Under assumption of small initial data, we establish the unique global solution by energy method. Moreover, we obtain th...In this article, we study the electromagnetic fluid system in three-dimensional whole space R^3. Under assumption of small initial data, we establish the unique global solution by energy method. Moreover, we obtain the time decay rates of the higher-order spatial derivatives of the solution by combining the L^p-L^q estimates for the linearized equations and an elaborate energy method when the L^1-norm of the perturbation is bounded.展开更多
As the base oil of the current flat-rheology synthetic drilling fluid is high in cost and not renewable, the biodiesel-based flat-rheology drilling fluid with low-cost, environmental protection and renewable advantage...As the base oil of the current flat-rheology synthetic drilling fluid is high in cost and not renewable, the biodiesel-based flat-rheology drilling fluid with low-cost, environmental protection and renewable advantage was studied. Based on the optimization of raw materials, a cheap, environment-friendly biodiesel of soybean oil ethyl ester with good fluidity at low temperature was selected as the base oil. By selecting high oil-water ratio and introducing cationic surfactant into the auxiliary emulsifier, the thickening of biodiesel-based emulsion caused by hydrolysis and saponification after high-temperature aging was effectively eliminated. The organoclay prepared with cationic modifier of hexadecyl trimethyl ammonium chloride was used to improve the rheologic properties, stability and fluid loss of the drilling fluid while preventing low-temperature thickening. A flat-rheology modifier was synthesized with dimer fatty acid and cocoanut fatty acid diethanolamide, which could form strong network structure in the biodiesel-based drilling fluid to adjust effectively rheological properties of the drilling fluid. A biodiesel-based flat-rheology drilling fluid system with the density of 1.2 g/cm^(3) has been formulated which has constant rheology in the temperature range of 2-90 ℃, temperature tolerance of 160 ℃, seawater salinity tolerance of 5%, shale cuttings tolerance of 10%, and is environmentally friendly.展开更多
Fine disseminated gold deposits occurring along the southeastern margin ofthe Yangtze Plate belong to the epithermal type resulting from different systems of oreforming fluids. According to their sources, the ore-form...Fine disseminated gold deposits occurring along the southeastern margin ofthe Yangtze Plate belong to the epithermal type resulting from different systems of oreforming fluids. According to their sources, the ore-forming fluids can be divided intofour systems: a) meteoric water system; b) oil-brine system; c) basin-brine system; andd) magmatic-formation water system. The four hydrothermal systems are responsiblefor four types of gold deposits, respectively The meteoric water system produces hotspring gold deposits. The basin-brines, which are derived from fissure water, structuralwater and absorbed water sealed up in strata, are responsible for the basin-brine-typedeposits. The oil-brine system, having the same source as the basin-brines, is characterizedby the involvment of organic matter and is responsible for the oil-brine-type deposits.Inclusion fluld data show that there are obvious differences in chemical compesition andcarbon, oxygen, hydrogen and sulfur isotopes for these hydrothermal systems. Differentmetalloenic provinces, in which one of the four systems is dominant, can be recognizedin the region.展开更多
In this paper, we introduced reservoir characteristics in Block Xiao-he-long and evaluate the performance of the existing killing fluid system. According to the production requirements, a anti-swelling and low damagin...In this paper, we introduced reservoir characteristics in Block Xiao-he-long and evaluate the performance of the existing killing fluid system. According to the production requirements, a anti-swelling and low damaging system of chemical agents suitable for this block was optimized, including anti-swelling agent, water lock inhibitor, fluid-loss agent additives, plus a corrosion inhibitor HS-1 developed by in the lab. The system is composed by base liquid (0.7%X + 2.0%KCl +0.05%SY-1+ 0.05%HS-1+2.0% DST-1 dissolved in water) and weighting material (NaCl) with its density adjustable range between 1.0g/ml and 1.2g/ml. Its anti-swelling ratio achieves 53.80%, and the reservoir permeability recovery ratio reaches more than 95.0%.展开更多
Based on the knowing geochemical characteristics of wall rock in the Mobin gold deposit and composition of fluid inclusion in ore,water rock experiments were carried out, important achievements are acquired as followi...Based on the knowing geochemical characteristics of wall rock in the Mobin gold deposit and composition of fluid inclusion in ore,water rock experiments were carried out, important achievements are acquired as following: Gold is mainly derived from the ore bearing wall rock,i.e., a series of epimetamorphic clastic gritstone, sandy slate, and tuffaceous slate in the Wuqiang Banxi Formation, Wuqiangxi Group. In thermal system with middle low temperature chlorine gold may be derived form stable complex ions, so it is quite important in gold metallogenic process. Sulphur and chlorine perform as the major negative ions throughout the gold activation and migration movement. The concentration of sulphur and chlorine ions, pH value and temperature are of deciding significance for gold activation, migration and precipitation.展开更多
There are many problems associated with coiled tubing drilling operations, such as great circulation pressure loss inside pipe, difficulties in weight on bit(WOB) transferring, and high probability of differential sti...There are many problems associated with coiled tubing drilling operations, such as great circulation pressure loss inside pipe, difficulties in weight on bit(WOB) transferring, and high probability of differential sticking. Aiming at these problems, solids-free brine drilling fluid system was developed on the basis of formulation optimization with brine base fluid experiment, which was evaluated and applied to field drilling. Based on the optimization of flow pattern regulator, salt-resisting filtrate reducer, high performance lubricant and bit cleaner, the basic formula of the solids-free brine drilling fluid system was formed: brine +(0.1%-0.2%) Na OH +(0.2%-0.4%) HT-XC +(2.0%-3.0%) YLJ-1 +(0.5%-2.0%) SDNR +(1.0%-2.5%) FT-1 A +(1.0%-5.0%) SD-505 + compound salt density regulator. Lab evaluation showed that the fluid had satisfactory temperature resistance(up to 150 ℃), excellent cuttings tolerance(up to 25%), and strong inhibition(92.7% cuttings recovery); Moreover, its lubrication performance was similar to that of all oil-based drilling fluid. The wellbore could be fairly cleaned at annular up-flow velocity of more than 0.8 m/s if the ratio of yield point to plastic viscosity was kept above 0.5. This fluid system has been applied in the drilling of three coiled tubing sidetracking wells in the Liaohe Oilfield, during which the system was stable and easy to adjust, resulting in excellent cuttings transportation, high ROP, regular hole size, and no down hole accidents. In summary, the solids-free brine drilling fluid system can meet the technical requirements of coiled tubing drilling.展开更多
To improve the thermal stability of starch in water-based drilling fluid,monoethanolamine(MEA)was added,and the effect was investigated by laboratory experiment.The experimental results show that the addition of monoe...To improve the thermal stability of starch in water-based drilling fluid,monoethanolamine(MEA)was added,and the effect was investigated by laboratory experiment.The experimental results show that the addition of monoethanolamine(MEA)increases the apparent viscosity,plastic viscosity,dynamic shear force,and static shear force of the drilling fluid,and reduces the filtration rate of drilling fluid and thickness of mud cake apparently.By creating hydrogen bonds with starch polymer,the monoethanolamine can prevent hydrolysis of starch at high temperature.Starch,as a natural polymer,is able to improve the rheological properties and reduce filtration of drilling fluid,but it works only below 121℃.The MEA will increase the thermal stability of starch up to 160℃.There is a optimum concentration of MEA,when higher than this concentration,its effect declines.展开更多
In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse wa...In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse water-based drilling fluid at home and abroad is analyzed. It is difficult to prevent and control the well collapse. Once the well wall instability problem occurs, it will often bring huge economic losses to the enterprises, and the underground safety accidents will occur. In order to ensure the stability of the well wall and improve the downhole safety, the key treatment agent of water-based collapse drilling fluid is selected, the anti-collapse drilling fluid system is formulated, the evaluation method of drilling fluid prevention performance is established, and a set of water-based drilling fluid system suitable for easy to collapse strata in China is selected to ensure the downhole safety. The development trend of high performance anti-collapse water-based drilling fluid is expected to provide a reference for the research of high performance anti-collapse water-based drilling fluid system and key treatment agent.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
With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve ...With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve the environmental protection and oil-gas reservoir protection problems of offshore oil drilling, a new synthetic basic drilling fluid system is developed. The basic formula is as follows: a basic fluid (80% Linear a-olefin + 20% Simulated seawater) + 2.5% nano organobentonite + 3.5% emulsifier RHJ-5<sup>#</sup> + 2.5% fluid loss agent SDJ-1 + 1.5% CaO + the right amount of oil wetting barite to adjust the density, and a multifunctional oil and gas formation protective agent YRZ has been developed. The performance was evaluated using a high-low-high-temperature rheometer, a high-temperature and high-pressure demulsification voltage tester, and a high-temperature and high-pressure dynamic fluid loss meter. The results show that the developed synthetic based drilling fluid has good rheological property, demulsification voltage ≥ 500 V, temperature resistance up to 160°C, high temperature and high pressure filtration loss < 3.5 mL. After adding 2% - 5% YRZ into the basic formula of synthetic based drilling fluid, the permeability recovery value exceeds 90% and the reservoir protection effect is excellent. The new synthetic deepwater drilling fluid is expected to have a good application prospect in offshore deepwater drilling.展开更多
文摘The ash mudstone in some oil formations is highly water-sensitive.The oil formation is fractured,and the risk of well leakage and collapse is not negligible.This study presents a countermeasure for well collapse prevention,based on a“force-chemistry synergistic balance”approach and the utilization of environmentally friendly and efficient hydration inhibitors.The relevance of this approach is demonstrated considering a drilling fluid system with the high potassium content.The analysis shows that the system can maintain good rheological properties,filtration loss and suspension stability even after aging at 130℃ for 16 h.The primary roll recovery of rock chips is better than 98%.The secondary rolling recovery rate is 89%.The rapid water loss is close to zero.The effects of carrying rock,sand,hydration inhibition and dispersion of drill chips are all noticeable.
基金The authors acknowledge the support of the National Key Basic Research Project No.G1999043206“Advanced School Key Teachers Supporting Program”of the Ministry of Education,the National Climbing Program of China No.95-pre-25 and 95-pre-39the“100 Trans-Century Science and Technology Talented Persons Cultivating Program”Foundation of the Ministry of Land and Mineral Resources No.9808.
文摘Based on an analysis of the fractal structures and mass transport mechanism of typical shear-fluid-ore formation system, the fractal dispersion theory of the fluid system was used in the dynamic study of the ore formation system. The model of point-source diffusive illuviation of the shear-fluid-ore formation system was constructed, and the numerical simulation of dynamics of the ore formation system was finished. The result shows that: (1) The metallogenic system have nested fractal structure. Different fractal dimension values in different systems show unbalance and inhomogeneity of ore-forming processes in the geohistory. It is an important parameter to symbolize the process of remobilization and accumulation of ore-forming materials. Also it can indicate the dynamics of the metallogenic system quantitatively to some extent. (2) In essence, the fractal dispersive ore-forming dynamics is a combination of multi-processes dominated by fluid dynamics and supplemented by molecule dispersion in fluids and fluid-rock interaction. It changes components and physico-chemical properties of primary rocks and fluids, favouring deposition and mineralization of ore-forming materials. (3) Gold ore-forming processes in different types of shear zones are quite different. (1) In a metallogenic system with inhomogeneous volumetric change and inhomogeneous shear, mineralization occurs in structural barriers in the centre of a shear zone and in geochemical barriers in the shear zone near its boundaries. But there is little possibility of mineralization out of the shear zone. (2) As to a metallogenic system with inhomogeneous volumetric change and simple shear, mineralization may occur only in structural barriers near the centre of the shear zone. (3) In a metallogenic system with homogeneous volumetric change and inhomogeneous shear, mineralization may occur in geochemical barriers both within and out of the shear zone.
文摘Fracturing fluid is the blood of fracturing construction, which is very important for fracturing, which requires that fracturing fluid needs to have good performance. The three commonly used fracturing fluids for unconventional oil and gas reservoir transformation are: 1) Guar gum fracturing fluid;2) Water-based emulsion slippery water fracturing fluid;3) Oil-based emulsion slippery water fracturing fluid. In this paper, water samples and other experimental data provided by Mahu Oilfield are used to evaluate three different fracturing fluid systems in laboratory. The formulas of the three different fracturing fluid systems are: 1) Water-based emulsion slippery water fracturing fluid is clean slippery water fracturing fluid 0.1% JHFR-2D drag reducer + 0.2% JHFD-2 multifunctional additive;2) Oil-based emulsion slippery water fracturing fluid 0.1% A agent + 0.2% B agent;3) Guar gum fracturing fluid 0.1% guanidine gum + 0.5% drainage aid + 0.3% demulsifier. The compatibility, drag reduction performance, reservoir damage, residue content, anti-swelling performance, surface interfacial tension, viscosity and other properties of three different slippery water fracturing fluid systems were studied. Through laboratory experiments, the comprehensive indicators show that clean slippery water fracturing fluid has obvious advantages.
基金supported jointly by the Fostering Plan Fund for Beyond-Century Excellent Talent and the Key Project of Science and Technology Research of the Ministry of Education(No.03178)the National Natural Science Foundation of China(No.40172036 an d No.40272051).
文摘Based on detailed and systematic researches of the geology of ore deposits, fluid inclusions and isotope geochemistry etc., and regarding the Late Paleozoic fluid system of the Yuebei Basin as an integrated object in this paper, we have revealed the temporo-spatial evolution law of the basin’s fluid system and discussed its ore-forming effects by simulating and analyzing the distribution of ore-forming elements, the fluid thermodynamics and dynamics of evolution processes of this basin. The results show that Late Paleozoic ore-forming fluid systems of the Yuebei Basin include four basic types as follows. (1) The sea floor volcanic-exhalation system developed during the rapid basin slip-extension stage in the Mid-Late Devonian, which affected the Dabaoshan region. It thus formed the Dabaoshan-type Cu-Pb-Zn-Fe sea floor volcanic-exhalation sedimentary deposits. (2) The compaction fluid system developed during the stable spreading and thermal subsidence-compression stage of the basin in the Mid-Late Devonian. The range of its effects extended all over the whole basin. It resulted in filling-metasomatic deposits, such as the Hongyan-type pyrite deposits and pyrite sheet within the Fankou-type Cu-Pb-Zn-S deposits. (3) The hot water circulation system of sea floor developed during the stage of basin uplifting and micro-aulacogen from the late Late Carboniferous to Middle Carboniferous. The range of its effects covered the Fankou region. It thus formed MVT deposits, such as the main orebody of the Fankou-type Pb-Zn-S deposits. (4) The gravity fluid system developed during the stage of fold uplifting and the basin closed from Middle Triassic to Jurassic, forming groundwater hydrothermal deposits, e.g. the veinlet Pb-Zn-calcite orebodies of the Fankou-type Pb-Zn-S deposits. Migration and concentration of the ore-forming fluids were constrained by the state of temporo-spatial distribution of its fluid potential. Growth faults not only converged the fluids and drove them to move upwards, but also the fluids often crossed the faults to the edges of the basin at the bottom of these faults and the lithologic interfaces, and even migrated to the basin’s edges from top to bottom along the faults, which may be one of the basic reasons for the stratabound deposits to cluster mainly along the contemporaneous faults on the inner border of the basin. The superposed mineralization resulting from the multi-stage activity of contemporaneous faults and ore-forming fluid systems in the basin may be one of the key factors for forming superlarge ore deposits.
基金The project supported by National Natural Science Foundation of China under Grant Nos.10547124,10475055,and 90503006the Youth Foundation of Shanghai Jiao Tong University
文摘A quite general coupled variable coefficient modified KdV (VCmKdV) equation in a two-layer fluid systemis derived by means of the reductive perturbation method.Making use of the CK's direct method,some similarityreductions of the coupled VCmKdV equation are obtained and their corresponding group explanations are discussed.Some exact solutions of the coupled equations are also presented.
文摘Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon reservoir. Due to the solid free system, the damage of solid phase particles on reservoir, especially low permeability oil and gas layer, can be greatly eliminated, at the same time, drilling fluid and completion fluid have greater compatibility. It will avoid that precipitation which is not compatible with drilling and completion fluid and generates damages on reservoir. And because mud cake of the solid free system is thin and resilient, it is conductive to improve cementing quality greatly. Experiments show that the formate drilling and completion system has good rheological property, strong inhibition ability, good lubricating performance, good compatibility with reservoir rocks and formation water at high temperature.
基金the National NaturalScience Foundation of China(Grant No.40272048)thegeological survey project of the Ministry of Land andResource(Grant No.K1.4-2-2)+1 种基金the Anhui Provincial Exccllent Youth Science and Technology Foundation(04045063) the Anhui Provincial Natural Scicnce Foundation(Grant No.01045202).
文摘Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore-forming fluid systems are classified in this article. It is proposed that the fluid ore-forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crustmantle interaction and magmatic-tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore-forming systems and geological backgrounds.
基金partially supported by the National Natural Science Foundation of China(11501373,11701380,11271381)Guangdong Provincial Culture of Seedling of China(2013LYM0081)+2 种基金the Natural Science Foundation of Guangdong Province(2017A030307022,2016A0300310019,2016A030307042)the Education Research Platform Project of Guangdong Province(2014KQNCX208)the Education Reform Project of Guangdong Province(2015558)
文摘In this article, we study the electromagnetic fluid system in three-dimensional whole space R^3. Under assumption of small initial data, we establish the unique global solution by energy method. Moreover, we obtain the time decay rates of the higher-order spatial derivatives of the solution by combining the L^p-L^q estimates for the linearized equations and an elaborate energy method when the L^1-norm of the perturbation is bounded.
基金Supported by the NSFC Innovative Research Group(51821092)NSFC Foundation(52004297)+1 种基金China Postdoctoral Science Foundation(BX20200384)China University of Petroleum(Beijing)Foundation(2462020XKBH00)。
文摘As the base oil of the current flat-rheology synthetic drilling fluid is high in cost and not renewable, the biodiesel-based flat-rheology drilling fluid with low-cost, environmental protection and renewable advantage was studied. Based on the optimization of raw materials, a cheap, environment-friendly biodiesel of soybean oil ethyl ester with good fluidity at low temperature was selected as the base oil. By selecting high oil-water ratio and introducing cationic surfactant into the auxiliary emulsifier, the thickening of biodiesel-based emulsion caused by hydrolysis and saponification after high-temperature aging was effectively eliminated. The organoclay prepared with cationic modifier of hexadecyl trimethyl ammonium chloride was used to improve the rheologic properties, stability and fluid loss of the drilling fluid while preventing low-temperature thickening. A flat-rheology modifier was synthesized with dimer fatty acid and cocoanut fatty acid diethanolamide, which could form strong network structure in the biodiesel-based drilling fluid to adjust effectively rheological properties of the drilling fluid. A biodiesel-based flat-rheology drilling fluid system with the density of 1.2 g/cm^(3) has been formulated which has constant rheology in the temperature range of 2-90 ℃, temperature tolerance of 160 ℃, seawater salinity tolerance of 5%, shale cuttings tolerance of 10%, and is environmentally friendly.
文摘Fine disseminated gold deposits occurring along the southeastern margin ofthe Yangtze Plate belong to the epithermal type resulting from different systems of oreforming fluids. According to their sources, the ore-forming fluids can be divided intofour systems: a) meteoric water system; b) oil-brine system; c) basin-brine system; andd) magmatic-formation water system. The four hydrothermal systems are responsiblefor four types of gold deposits, respectively The meteoric water system produces hotspring gold deposits. The basin-brines, which are derived from fissure water, structuralwater and absorbed water sealed up in strata, are responsible for the basin-brine-typedeposits. The oil-brine system, having the same source as the basin-brines, is characterizedby the involvment of organic matter and is responsible for the oil-brine-type deposits.Inclusion fluld data show that there are obvious differences in chemical compesition andcarbon, oxygen, hydrogen and sulfur isotopes for these hydrothermal systems. Differentmetalloenic provinces, in which one of the four systems is dominant, can be recognizedin the region.
文摘In this paper, we introduced reservoir characteristics in Block Xiao-he-long and evaluate the performance of the existing killing fluid system. According to the production requirements, a anti-swelling and low damaging system of chemical agents suitable for this block was optimized, including anti-swelling agent, water lock inhibitor, fluid-loss agent additives, plus a corrosion inhibitor HS-1 developed by in the lab. The system is composed by base liquid (0.7%X + 2.0%KCl +0.05%SY-1+ 0.05%HS-1+2.0% DST-1 dissolved in water) and weighting material (NaCl) with its density adjustable range between 1.0g/ml and 1.2g/ml. Its anti-swelling ratio achieves 53.80%, and the reservoir permeability recovery ratio reaches more than 95.0%.
基金The Doctoral Foundation of the Education Ministry of China(970 53 0 1) The Natural Science Foundationof Hunan province (97JJ2 0 5)
文摘Based on the knowing geochemical characteristics of wall rock in the Mobin gold deposit and composition of fluid inclusion in ore,water rock experiments were carried out, important achievements are acquired as following: Gold is mainly derived from the ore bearing wall rock,i.e., a series of epimetamorphic clastic gritstone, sandy slate, and tuffaceous slate in the Wuqiang Banxi Formation, Wuqiangxi Group. In thermal system with middle low temperature chlorine gold may be derived form stable complex ions, so it is quite important in gold metallogenic process. Sulphur and chlorine perform as the major negative ions throughout the gold activation and migration movement. The concentration of sulphur and chlorine ions, pH value and temperature are of deciding significance for gold activation, migration and precipitation.
基金Supported by the China National Science and Technology Major Project(2016ZX05020-004)
文摘There are many problems associated with coiled tubing drilling operations, such as great circulation pressure loss inside pipe, difficulties in weight on bit(WOB) transferring, and high probability of differential sticking. Aiming at these problems, solids-free brine drilling fluid system was developed on the basis of formulation optimization with brine base fluid experiment, which was evaluated and applied to field drilling. Based on the optimization of flow pattern regulator, salt-resisting filtrate reducer, high performance lubricant and bit cleaner, the basic formula of the solids-free brine drilling fluid system was formed: brine +(0.1%-0.2%) Na OH +(0.2%-0.4%) HT-XC +(2.0%-3.0%) YLJ-1 +(0.5%-2.0%) SDNR +(1.0%-2.5%) FT-1 A +(1.0%-5.0%) SD-505 + compound salt density regulator. Lab evaluation showed that the fluid had satisfactory temperature resistance(up to 150 ℃), excellent cuttings tolerance(up to 25%), and strong inhibition(92.7% cuttings recovery); Moreover, its lubrication performance was similar to that of all oil-based drilling fluid. The wellbore could be fairly cleaned at annular up-flow velocity of more than 0.8 m/s if the ratio of yield point to plastic viscosity was kept above 0.5. This fluid system has been applied in the drilling of three coiled tubing sidetracking wells in the Liaohe Oilfield, during which the system was stable and easy to adjust, resulting in excellent cuttings transportation, high ROP, regular hole size, and no down hole accidents. In summary, the solids-free brine drilling fluid system can meet the technical requirements of coiled tubing drilling.
文摘To improve the thermal stability of starch in water-based drilling fluid,monoethanolamine(MEA)was added,and the effect was investigated by laboratory experiment.The experimental results show that the addition of monoethanolamine(MEA)increases the apparent viscosity,plastic viscosity,dynamic shear force,and static shear force of the drilling fluid,and reduces the filtration rate of drilling fluid and thickness of mud cake apparently.By creating hydrogen bonds with starch polymer,the monoethanolamine can prevent hydrolysis of starch at high temperature.Starch,as a natural polymer,is able to improve the rheological properties and reduce filtration of drilling fluid,but it works only below 121℃.The MEA will increase the thermal stability of starch up to 160℃.There is a optimum concentration of MEA,when higher than this concentration,its effect declines.
文摘In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse water-based drilling fluid at home and abroad is analyzed. It is difficult to prevent and control the well collapse. Once the well wall instability problem occurs, it will often bring huge economic losses to the enterprises, and the underground safety accidents will occur. In order to ensure the stability of the well wall and improve the downhole safety, the key treatment agent of water-based collapse drilling fluid is selected, the anti-collapse drilling fluid system is formulated, the evaluation method of drilling fluid prevention performance is established, and a set of water-based drilling fluid system suitable for easy to collapse strata in China is selected to ensure the downhole safety. The development trend of high performance anti-collapse water-based drilling fluid is expected to provide a reference for the research of high performance anti-collapse water-based drilling fluid system and key treatment agent.
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.
文摘With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve the environmental protection and oil-gas reservoir protection problems of offshore oil drilling, a new synthetic basic drilling fluid system is developed. The basic formula is as follows: a basic fluid (80% Linear a-olefin + 20% Simulated seawater) + 2.5% nano organobentonite + 3.5% emulsifier RHJ-5<sup>#</sup> + 2.5% fluid loss agent SDJ-1 + 1.5% CaO + the right amount of oil wetting barite to adjust the density, and a multifunctional oil and gas formation protective agent YRZ has been developed. The performance was evaluated using a high-low-high-temperature rheometer, a high-temperature and high-pressure demulsification voltage tester, and a high-temperature and high-pressure dynamic fluid loss meter. The results show that the developed synthetic based drilling fluid has good rheological property, demulsification voltage ≥ 500 V, temperature resistance up to 160°C, high temperature and high pressure filtration loss < 3.5 mL. After adding 2% - 5% YRZ into the basic formula of synthetic based drilling fluid, the permeability recovery value exceeds 90% and the reservoir protection effect is excellent. The new synthetic deepwater drilling fluid is expected to have a good application prospect in offshore deepwater drilling.
