http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
오늘 본 자료
Diaz, Melvin B.,Kim, Kwang Yeom,Kang, Tae-Ho,Shin, Hyu-Soung Elsevier 2018 Geothermics Vol.72 No.-
<P><B>Abstract</B></P> <P>Drilling parameters are analyzed here to improve forecasting of the rate of penetration (ROP) in enhanced geothermal systems (EGSs). Data recorded during drilling a 4.2-km-deep well at a pilot EGS project in South Korea were analyzed. The greatly fluctuating ROP values were smoothed using a fast Fourier transform filter. Two drilling optimization methods (multiple regression and artificial neural networks) then evaluated the effect of smoothing: it improved ROP prediction in both cases, with over 90% correlation at relatively low degrees of filtering. A methodology to optimize the degree of smoothness for a given drilling data set is suggested.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Analysis of drilling parameters recorded during drilling of a 4.2 km depth well. </LI> <LI> The drilling data comes from an Enhanced Geothermal System (EGS) project. </LI> <LI> The fluctuating ROP recorded values were smoothed using an FFT filter. </LI> <LI> Multiple regression and a neural network evaluated the filtering effect on ROP prediction. </LI> <LI> A methodology to optimize the degree of smoothness is suggested. </LI> </UL> </P>
Fluid Infiltration Effect on Breakdown Pressure in Laboratory Hydraulic Fracturing Tests
Melvin B. Diaz,정성규,이경원,김광염 대한지질공학회 2022 지질공학 Vol.32 No.3
Observations on the influence of the fluid infiltration on the breakdown pressure during laboratory hydraulic fracturing tests, along with an analysis of the applicability of the breakdown pressure prediction for cylindrical samples using Quasi-static and Linear Elastic Fracture Mechanics approaches were carried out. These approaches consider fluid infiltration through the so-called radius of fluid infiltration or crack radius, a parameter that is not a material property. Two sets of tests under pressurization rate controlled and injection rate controlled tests were used to evaluate the applicability of these methods. The difficulty of the estimation of the radius of fluid infiltration was solved by back calculating this parameter from an initial set of tests, and later, the obtained relationships were used to predict breakdown pressures for a second set of tests. The results showed better predictions for the injection rate than for the pressurization rate tests, with average errors of 3.4% and 18.6%, respectively. The larger error was attributed to differences in the testing conditions for the pressurization rate tests, which had different applied vertical pressures. On the other hand, for the tests carried out under constant injection rate, the Linear Elastic Fracture Mechanics solution reported lower errors compared to the Quasi-static solution, with values of 3% and 3.8%, respectively. Moreover, a sensitivity analysis illustrated the influence of the radius of fluid penetration or crack radius and the tensile strength on the breakdown pressure, suggesting a need for a careful estimation of these values. Then, the calculation of breakdown pressure considering fluid infiltration in cylindrical samples under triaxial conditions is possible, although larger data sets are desirable to validate and derive better relations.