Elastic impedance inversion for stress indicator in weakly orthorhombic media

Hydraulic fracturing is a crucial technology for improving permeability and production of shale reservoirs.The precise estimation of the stress distribution has a significant guidance for optimizing the placement of hydraulic fracturing.Assuming that the shale gas reservoir is a weakly anisotropic medium with orthorhombic symmetry,a new stress indicator parameterized by rock mechanical parameters and fracture parameters is firstly presented to predict the differential horizontal stress ratio in shale gas reservoirs.Then,we derive a novel simplified P-to-P reflection coefficient and a logarithmic normalized elastic impedance(EI)as a function of Young’s modulus,Poisson’s ratio,Thomsen’s WA parameterδband normal excess compliance Z_(N).Next,we adopt azimuthal EI inversion in a Bayesian framework to estimate rock mechanics parameters and fracture parameters directly on a fractured shale gas field seismic data.Finally,the stress indicator is determined by utilizing four inverted parameters.Synthetic examples demonstrate that the proposed approach produces stable parameter estimates even with moderate noise,verifying the feasibility and effectiveness of the method.Test on a field data set illustrates that the inversion results can be reasonably estimated,and the stress indicator derived by the inversion accords with the geomechanics result.Compared with the previous method,the new stress indicator has a higher capability to describe stress characteristics in the shale reservoir.We conclude that this stress evaluation procedure can provide reliable guidance for well location deployment and hydraulic fracturing reformation.

Acupuncture for dystonia in brain-type Wilson’s disease with internal retention of damp heat pattern:A randomized clinical trail

Objective:To observe the clinical efficacy of acupuncture on dystonia in brain-type Wilson’s disease(WD)with internal retention of damp heat pattern.Methods:A total of 60 patients with WD dystonia with internal retention of damp heat pattern were randomized into acupuncture and medication groups using a random number table,with 30 participants in each group.All patients had a low-copper diet and consumed dimercaptopropanesulfonate sodium(DMPS) for copper excretion.In the acupuncture group,on the base of the same treatment as that given to the medication group,acupuncture was applied at Baihui(百会GV20),Shenting(神庭GV24),Chéngjiāng(承浆CV4),Jiānyú(肩髃L15),Nàoshū(臑俞SI10),Wàiguān(外关TE5),Nèiguān(内关PC6),Shǒusānlǐ(手三里LI10),Hégǔ(合谷LI4),Yángxī(阳溪LI5),Huántiào(环跳GB30),Bìguān(髀关ST31),Yánglíngquán(阳陵泉GB34),Fēnglóng(丰隆ST40),Zúsānlǐ(足三里ST36),Sānyīnjiāo(三阴交SP6),Xuánzhōng(悬钟GB39),and Xíngjiān(行间LR2).Before and 24 days after treatment,the modified Ashworth scale(MAS) and BurkeFahn-Marsden dystonia rating scale(BFMDRS) were used to evaluate dystonia symptoms.The allocation scheme was concealed for the outcome assessors.Results:The data of 30 cases were analyzed in each group.Before treatment,the MAS score difference between the acupuncture and medication groups was not statistically significant(P> 0.05).Compared with the score before treatment,the MAS score was lower significantly in both the acupuncture group(2.63±0.76 vs 4.50 ± 0.78) and medication group(3.30 ± 0.65 vs 4.40 ± 0.77) after treatment(both P <0.05).After treatment,the MAS score in the acupuncture group was significantly lower than that in the medication group(P <0.01).Before treatment,the BFMDRS score was not significantly different between the two groups(P> 0.05).Compared with the score before treatment,the BFMDRS score was significantly lower in both the acupuncture(64.97 ± 14.26 vs 85.23± 16.99) and medication groups(11.33 ± 2.60 vs 75.40 ± 16.25) after treatment(both P <0.05).The BFMDRS score of the acupuncture group was lower than that of the medication group after treatment(P <0.05).During treatment,1 case had allergic reaction of DMPS in the acupuncture group,manifested as reddish skin and skin rashes,and the allergic symptoms disappeared after anti-allergic treatment.There was no any adverse reaction in the medication group.Conclusion:Combined treatment with acupuncture and Western medication is significantly effective against dystonia in brain-type WD with internal retention of damp heat pattern.