Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pr...Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pressure,complicated structure and anisotropic,high flow-resistance and micro pore throats etc,.Generally they also have lots of natural micro fractures,probably leading to stress sensibility.Main damaging factors in such reservoirs are water-sensibility and water-blocking caused by invasive fluids during drilling and production operations.Once damaged,formation permeability can rarely recovered.Numerous studies have shown that damaging extent of water-blocking ranges from 70% to 90%.Main damaging mechanisms and influencing factors of water-blocking were systematically analyzed.Also some feasible precaution or treating approaches of water-blocking were put forward.In a laboratory setting,a new multi-functional drilling fluid composed mainly of amphion polymer,sulfonation polymer,high effectively preventive water-blocking surfactants,ideal packing temporary bridging agents(TBA) and film-forming agents,etc.,were developed.New low-damage drilling fluids has many advantages,such as good rheological properties,excellent effectiveness of water-blocking prevention,good temporary plugging effect,low filtration and ultra-low permeability(API filtration≤5 mL,HTHP filtration≤10 mL,mud cake frictional coefficient≤0.14,permeability recovery>81%),can efficiently prevent or minimize damage,preserve natural formation and enhance comprehensive development-investment effect in TUHA Jurassic dense sandstone reservoir formation with low-permeability,the only one developing integrated condense gas field.Some references can be provided to similar reservoir formations.展开更多
The study carried out here was focused on developing conventional monolithic controlled release matrix tablet of Atorvastatin calcium using carbomer as release controlling polymer. This system ensures the drug release...The study carried out here was focused on developing conventional monolithic controlled release matrix tablet of Atorvastatin calcium using carbomer as release controlling polymer. This system ensures the drug release at the alkaline pH region where the drug has got maximum solubility. Further the study was concentrated on comparing the impact of gelling agent polyvinyl pyrrolidone on drug release. Quality by design tools were considered during formulation development and the polymer concentrations were optimized adopting the statistical tool, design of experiments (DoE). The optimized formulation of present study exhibited desired controlled drug release characteristics in the alkaline pH conditions and at acidic environment the drug dissolution was minimal as intended.展开更多
The low-permeability oil and gas resources of our country are quite common and abundant. Their reserve has accounted for one-fifth of total oil reserves of our country, and their yield has constituted the important pa...The low-permeability oil and gas resources of our country are quite common and abundant. Their reserve has accounted for one-fifth of total oil reserves of our country, and their yield has constituted the important part of national petroleum annual yield, but its development is very difficult. Polymer gel technology is a technical method of improving sweep efficiency in recent years which substantially increases the viscosity of the polymer solution by adding a crosslinking agent to the polymer produced by intramolecular or intermolecular crosslinking.展开更多
基金Project(50574061) supported by the National Natural Science Foundation of China
文摘Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pressure,complicated structure and anisotropic,high flow-resistance and micro pore throats etc,.Generally they also have lots of natural micro fractures,probably leading to stress sensibility.Main damaging factors in such reservoirs are water-sensibility and water-blocking caused by invasive fluids during drilling and production operations.Once damaged,formation permeability can rarely recovered.Numerous studies have shown that damaging extent of water-blocking ranges from 70% to 90%.Main damaging mechanisms and influencing factors of water-blocking were systematically analyzed.Also some feasible precaution or treating approaches of water-blocking were put forward.In a laboratory setting,a new multi-functional drilling fluid composed mainly of amphion polymer,sulfonation polymer,high effectively preventive water-blocking surfactants,ideal packing temporary bridging agents(TBA) and film-forming agents,etc.,were developed.New low-damage drilling fluids has many advantages,such as good rheological properties,excellent effectiveness of water-blocking prevention,good temporary plugging effect,low filtration and ultra-low permeability(API filtration≤5 mL,HTHP filtration≤10 mL,mud cake frictional coefficient≤0.14,permeability recovery>81%),can efficiently prevent or minimize damage,preserve natural formation and enhance comprehensive development-investment effect in TUHA Jurassic dense sandstone reservoir formation with low-permeability,the only one developing integrated condense gas field.Some references can be provided to similar reservoir formations.
文摘The study carried out here was focused on developing conventional monolithic controlled release matrix tablet of Atorvastatin calcium using carbomer as release controlling polymer. This system ensures the drug release at the alkaline pH region where the drug has got maximum solubility. Further the study was concentrated on comparing the impact of gelling agent polyvinyl pyrrolidone on drug release. Quality by design tools were considered during formulation development and the polymer concentrations were optimized adopting the statistical tool, design of experiments (DoE). The optimized formulation of present study exhibited desired controlled drug release characteristics in the alkaline pH conditions and at acidic environment the drug dissolution was minimal as intended.
文摘The low-permeability oil and gas resources of our country are quite common and abundant. Their reserve has accounted for one-fifth of total oil reserves of our country, and their yield has constituted the important part of national petroleum annual yield, but its development is very difficult. Polymer gel technology is a technical method of improving sweep efficiency in recent years which substantially increases the viscosity of the polymer solution by adding a crosslinking agent to the polymer produced by intramolecular or intermolecular crosslinking.
