Abstract: The present disclosure provides a method for photo-curing 4D printing of a multi-layer structure with an adjustable shape recovery speed, and a multi-layer structure printed thereby. The multi-layer structure printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed includes a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units includes two slow layers, a fast layer, and a transition layer; and the fast layer is arranged between the two slow layers, and the transition layer is arranged between at least one of the two slow layers and the fast layer. In the present disclosure, a low cross-linking layer is doped with a nanocarbon light-absorbing material to solve the problem that the low cross-linking layer is prone to over-curing when a high cross-linking layer is printed on the low cross-linking layer.

Abstract: A quantitative evaluation method for integrity and damage evolution of a cement sheath in an oil-gas well is provided based on a fractal theory, an image processing technology, structural features and failure mechanisms of a casing-cement sheath-formation combination. The method uses correlations among fractal dimensions of casing-cement sheath interface morphology, cement sheath microscopic pore morphology, particle morphology of an initial blank group, and macroscopic mechanical properties including a radial cementing strength of the cement sheath interface, a tensile strength, and a compressive strength to quantitatively evaluate the integrity of the cement sheath of the blank group.

Abstract: A structural stabilizer for a fiber and proppant complex to enhance proppant migration and placement in a fractured well during propping and a preparation method thereof are provided. The structural stabilizer consists of: water, inorganic salt, kaolinite, nitrogen-doped modified graphene oxide, anionic surfactant, non-ionic alkyl polyglucoside, and polyacrylamide. The structural stabilizer improves bonding between a proppant and a fiber when slick water is used in stimulated reservoir volume (SRV) fracturing, prevents separation of the fiber and the proppant during migration, thereby reducing escape rate of the fiber from the fiber and proppant complex.

Abstract: An image capturing system includes a center point location, and a circular light source ring centered on the center point location. Light sources are on the circular light source ring, and each emit light in one of a number of spectral bandwidths. The image capturing system also includes circular camera rings, where each circular camera ring is centered on the center point location, where each circular camera ring includes camera locations which are equally spaced apart. The image capturing system also includes one or more cameras configured to capture images of an object from each of the camera locations of each particular circular camera ring, where the images captured from the camera locations of each particular circular camera ring are captured in one of the different spectral bandwidths, and where the object is illuminated by the light sources of the light source ring while each of the images are captured.

Abstract: An image capturing system includes a center point location, and a circular light source ring centered on the center point location. Light sources are on the circular light source ring, and each emit light in one of a number of spectral bandwidths. The image capturing system also includes circular camera rings, where each circular camera ring is centered on the center point location, where each circular camera ring includes camera locations which are equally spaced apart. The image capturing system also includes one or more cameras configured to capture images of an object from each of the camera locations of each particular circular camera ring, where the images captured from the camera locations of each particular circular camera ring are captured in one of the different spectral bandwidths, and where the object is illuminated by the light sources of the light source ring while each of the images are captured.