Journal of China University of Petroleum (Edition of Natural Science)

Fracture weakness inversion based on reflection amplitude Fourier coefficient

Quantitative inversion of fracture weakness plays an important role in fracture prediction. Considering reservoirs with a set of vertical fractures as horizontal transversely isotropic media, the logarithmic normalized azimuthal elastic impedance (EI) is rewritten in terms of Fourier coefcients (FCs), the 90° ambiguity in the azimuth estimation of the symmetry axis is resolved by judging the sign of the second FC, and we choose the FCs with the highest sensitivity to fracture weakness and present a feasible inversion workfow for fracture weakness, which involves: (1) the inversion for a

Wellbore temperature profiling for deepwater multi-gradient drilling

In order to study the distribution law of temperature in deep water CML dual-gradient drilling wellbore, the coupling relationship between wellbore temperature, pressure, drilling fluid density and rheological properties was comprehensively considered, and the transient heat transfer model of deep water CML dual-gradient drilling wellbore was established in combination with the characteristics of deep-water CML dual-gradient drilling process and the law of energy conservation. Based on an example well, the effects of cycle time and drilling fluid physical parameters on annulus temperature w

Seismic horizon picking technology based on improved DNA algorithms

Picking the reflection horizon is an important step in velocity inversion and seismic interpretation. Manual picking is time-consuming and no longer suitable for current large-scale seismic data processing. Automatic algorithms using different seismic attributes such as instantaneous phase or dip attributes have been proposed. However, the computed attributes are usually inaccurate near discontinuities. The waveforms in the horizontal direction often change dramatically, which makes it difficult to track a horizon using the similarity of attributes. In this paper, we propose a novel method

Study on fracture toughness of X80 pipeline steel based on small punch test

Evaluating the strength properties of materials of an in-service pipeline without shutting down transportation has been always a challenge. A novel and non-destructive method for determining the true stress-strain curve of pipeline steel based on backpropagation artificial neural network and small punch test is proposed in this study. The elastoplastic mechanical properties of the pipeline steels could be obtained by this method. The load-displacement curves of 2261 groups of different hypothetical materials were obtained by the finite element model of small punch test within Gurson-Tvergaa

A new drilling fluid technology based on supramolecular chemistry

Based on supramolecular chemistry, a rheology modifier CFZTQ-1 for oil base drilling fluids was developed, and an innovative high-density organoclay-free oil base drilling fluid system centering on CFZTQ-1 was designed, evaluated and applied in the field. CFZTQ-1 can strongly increase the elasticity of invert emulsion due to the supramolecular structure assembled in water phase; CFZTQ-1 has stronger effect in elevating the yield point and suspension ability than several foreign rheology modifiers; the synergistic effect with organoclay also makes CFZTQ-1 available in traditional clay-contai

Journal of China University of Petroleum (Edition of Natural Science)