Lost circulations have presented great challenges to the petroleum industry, causing great expenditures of cash and time to fighting the problem. Probably the most problematic situations are the naturally fractured fo...Lost circulations have presented great challenges to the petroleum industry, causing great expenditures of cash and time to fighting the problem. Probably the most problematic situations are the naturally fractured formations where the operator may face total loss with no mud return in the annular. The voids or large fracture encountered in this case are often far too large to be plugged with conventional Lost Circulation Material. This paper will give a detailed introduction on a novel composite gel material usable to control severe losses and pressurization sealing. The plugging mechanics of this new composite gel material, which is different from conventional lost circulation materials, were elaborated as well. In addition, the properties of the new composite gel material such as thermostability, sealing strength and bearing resistance are characterized with specific experimental devices. The experimental results proved that the breakdown pressure of the new plugging reached more than 20MPa, and the maximum degraded temperature can be exceed 130℃. The field application at 4 wells in Puguang gas field, SINOPEC, demonstrated that the new composite gel material solved the serious loss in Ordovician carbonate fractured formation successfully and guaranteed the following completion cement operation smoothly. The composite gel sealing slurries, which was easily prepared on site, gives remarkable properties regarding pumping through drill pipes, adjustment of setting time and excellent sealing strength of the lost zone sealing, additionally, the whole pressurization sealing process was complicated within only ten hours. The on-site results show that the plugging ratio of the new composite gel was reached 100%, and the success rate of sealing operation kept above 80%.Thus the new LCM can guarantee safe drilling jobs and save operation cost more effectively.展开更多
Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from ...Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from cornea is prevented, warm tear is lay- ered across corneal surface and the vessels of the palpebral conjunctiva provide heat to anterior eye. In most of the thermal models in human eye that are found in literatures, effect of blinking is not included, simulation is carried out only in open eye. Thus, in this paper, thermal effects of blinking are investigated using one-dimensional finite element method in transient state case. The bio-heat transfer process is simulated during different blinking rates, lid closure and opening. The simulation is carried out using normal and extreme values of ambient temperatures, blood temperatures, evaporation rates, blood perfusion rates, and lens thermal conduetivities. Blinking is found to increase corneal and lens temperature by 1.29℃ and 0.78℃ respectively when compared to open eye. The results obtained from this model are useful in predicting temperature distribution in different laser eye surgeries, hyperthermia and cryosurgery treatment of eyelid carci- noma, choroidal melanoma and can be used for diagnosing temperature-related diseases.展开更多
文摘Lost circulations have presented great challenges to the petroleum industry, causing great expenditures of cash and time to fighting the problem. Probably the most problematic situations are the naturally fractured formations where the operator may face total loss with no mud return in the annular. The voids or large fracture encountered in this case are often far too large to be plugged with conventional Lost Circulation Material. This paper will give a detailed introduction on a novel composite gel material usable to control severe losses and pressurization sealing. The plugging mechanics of this new composite gel material, which is different from conventional lost circulation materials, were elaborated as well. In addition, the properties of the new composite gel material such as thermostability, sealing strength and bearing resistance are characterized with specific experimental devices. The experimental results proved that the breakdown pressure of the new plugging reached more than 20MPa, and the maximum degraded temperature can be exceed 130℃. The field application at 4 wells in Puguang gas field, SINOPEC, demonstrated that the new composite gel material solved the serious loss in Ordovician carbonate fractured formation successfully and guaranteed the following completion cement operation smoothly. The composite gel sealing slurries, which was easily prepared on site, gives remarkable properties regarding pumping through drill pipes, adjustment of setting time and excellent sealing strength of the lost zone sealing, additionally, the whole pressurization sealing process was complicated within only ten hours. The on-site results show that the plugging ratio of the new composite gel was reached 100%, and the success rate of sealing operation kept above 80%.Thus the new LCM can guarantee safe drilling jobs and save operation cost more effectively.
文摘Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from cornea is prevented, warm tear is lay- ered across corneal surface and the vessels of the palpebral conjunctiva provide heat to anterior eye. In most of the thermal models in human eye that are found in literatures, effect of blinking is not included, simulation is carried out only in open eye. Thus, in this paper, thermal effects of blinking are investigated using one-dimensional finite element method in transient state case. The bio-heat transfer process is simulated during different blinking rates, lid closure and opening. The simulation is carried out using normal and extreme values of ambient temperatures, blood temperatures, evaporation rates, blood perfusion rates, and lens thermal conduetivities. Blinking is found to increase corneal and lens temperature by 1.29℃ and 0.78℃ respectively when compared to open eye. The results obtained from this model are useful in predicting temperature distribution in different laser eye surgeries, hyperthermia and cryosurgery treatment of eyelid carci- noma, choroidal melanoma and can be used for diagnosing temperature-related diseases.
