The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and denta...The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO2/3- and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly, The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO2/3-and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO2/3-can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO2/3- to be located in the B sites.展开更多
Petrophysicists and reservoir engineers utilise the capillary pressure and saturation-height function for calculating the water saturation of any reservoir,at a given height above the free water level.The results have...Petrophysicists and reservoir engineers utilise the capillary pressure and saturation-height function for calculating the water saturation of any reservoir,at a given height above the free water level.The results have a big impact on reserve estimation.The majority of capillary pressure studies are carried out in labs with core data.Cores,on the other hand,are usually altered from their original state before being delivered to laboratories.Moreover,the accuracy of discrete sets of core data in describing entire reservoir parameters,is still up for debate.Prediction of the capillary pressure curve in reservoir condition is an important subject that is challenging to perform.The use of nuclear magnetic resonance(NMR)logs for oil and gas exploration has grown in popularity over the last few decades.However,most of the time the utilization of the data is limited for evaluating porosity-permeability,distributions and computation of irreducible water saturation.After the advent of fluid substitution methods,NMR T_(2)distributions may now be used to synthesize core equivalent capillary pressure curves.Using fluid substitution workflow,our study introduces a better approach for obtaining capillary pressure curves from the NMR T_(2)distribution.The available core data has been used to calculate calibration parameters for better saturation height modelling.The workflow introduces a novel approach in resistivity independent saturation computation.In the exploratory wells of our study area,computed water saturation derived from the saturation height function exhibits encouraging agreement with resistivity based water saturation from multi-mineral model.The NMR based saturation height modelling approach has been included in study area for the first time so far.展开更多
文摘The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO2/3- and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly, The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO2/3-and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO2/3-can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO2/3- to be located in the B sites.
基金The authors gratefully appreciate the support of Oil and Natural Gas Corporation,for providing data and permission to carry out the work under the CoEOGE project:RD/0120-PSUCE19-001.
文摘Petrophysicists and reservoir engineers utilise the capillary pressure and saturation-height function for calculating the water saturation of any reservoir,at a given height above the free water level.The results have a big impact on reserve estimation.The majority of capillary pressure studies are carried out in labs with core data.Cores,on the other hand,are usually altered from their original state before being delivered to laboratories.Moreover,the accuracy of discrete sets of core data in describing entire reservoir parameters,is still up for debate.Prediction of the capillary pressure curve in reservoir condition is an important subject that is challenging to perform.The use of nuclear magnetic resonance(NMR)logs for oil and gas exploration has grown in popularity over the last few decades.However,most of the time the utilization of the data is limited for evaluating porosity-permeability,distributions and computation of irreducible water saturation.After the advent of fluid substitution methods,NMR T_(2)distributions may now be used to synthesize core equivalent capillary pressure curves.Using fluid substitution workflow,our study introduces a better approach for obtaining capillary pressure curves from the NMR T_(2)distribution.The available core data has been used to calculate calibration parameters for better saturation height modelling.The workflow introduces a novel approach in resistivity independent saturation computation.In the exploratory wells of our study area,computed water saturation derived from the saturation height function exhibits encouraging agreement with resistivity based water saturation from multi-mineral model.The NMR based saturation height modelling approach has been included in study area for the first time so far.
