Haotian Zhang

Problems such as well loss and collapses in deep shale gas drilling are most often due to the development of cracks in the shale formation, resulting in significant leaks of drilling fluid, the sticking and burrowing of drilling tools, and other engineering accidents. In addition, the horizontal sections of wells are very long and issues of friction, rock transport, and formation contamination loom large. As a result, the performance of drilling fluids directly affects drilling efficiency, engineering accident rates, and reservoir protection effects. We first analyze the mechanisms of each emulsifier in an oil-based drilling fluid formulation and the filtration reduction mechanisms, taking into account the collapse-prone and abnormally high-pressure characteristics of shale formations. We undertake an experimental evaluation and optimization of polymeric surfactants, such as primary and secondary emulsions for high-performance oil-based drilling fluids. The design of rigid and deformable nano-micron plugging materials with a reasonable particle size range was achieved, and we obtained a low Oil—Water ratio and high-density oil-based drilling fluid system, with temperature resistance of 200 °C, an Oil—Water ratio as low as 70:30, compressive fracturing fluid pollution of 10%, and a maximum density of 2.6 g/cm³. The reuse rate reached 100%. The developed oil-based drilling fluid system with strong plugging, a high density, and a low Oil—Water ratio suitable for deep shale gas can effectively seal the well wall, reduce liquid invasion, prevent the wall from collapsing, reduce mud leakage, reduce the consumption of oil-based drilling fluid, improve the utilization rate of old mud, and reduce drilling costs.

We constructed and investigated a high-speed broadband spectroscopic ellipsometric system with 12 polarization channels and a 2-D charge-coupled device. The system without any mechanically moving component completes the measurements of more than 10 000 polarization signals at 889 data points in a wavelength range of 400–800 nm within 150 ms, with a spectral resolution better than 1 nm. An integrated analyzer consisting of 12 subanalyzers was employed to obtain the light of different polarization states simultaneously. The spectral distribution of different polarization channels was acquired by the spectral data acquisition system in parallel mode. Two kinds of data processing methods were applied to analyze the light intensities of different channels to obtain the ellipsometric information and other physical parameters of the material over a broad spectral range. According to the analysis of measurement results of gold and silicon bulk, and tantalum pentoxide film, the reliability of the proposed instrument was verified, showing application prospects in the field where in situ spectral monitoring is required.

We propose an accurate and rapid azimuth calibration method for polarizing elements in ellipsometry. Over 200 calibrations were achieved simultaneously at different wavelength points in a spectral range of 550–650 nm without any calibrated element. The azimuth of the polarizer was determined from the differential spectral analysis on the ellipse azimuth of reflected light. The information of the ellipse azimuth is experimentally acquired in the spectral range by a rotating polarizing element and a spectrometer. The presented method was performed and verified with Si and Au bulk, respectively, showing reliability and feasibility for efficient and reliable calibration in ellipsometry.

Considering characteristics of complex carbonate reservoirs (e.g., high depth, high temperature, and fracture cave development), this paper simulates expansion of the acid wormhole when combining diverting acid and a solid diverting agent f