Study on Acid Fracturing Technology for Carbonate Reservoirs in Ordos Basin

Acid fracturing, a key stimulation technology, has been widely applied in carbonate formations, which have the complex reservoir space and natural fracture. However, the conventional acid fracturing technology has limitations in target reservoir due to serious acid leakage and rapid acid-rock reaction speed. Therefore, a deep-penetration acid fracturing technology was proposed to enhance the stimulation effect. The reservoir basic physical properties, such as permeability and porosity, microstructure characteristic of pore throats, mineral composition, and rock mechanics characteristics, were systemically investigated by a series of laboratory experiments. The acid system was also optimized by evaluating rheological properties and residual acid damage. Furthermore, the most important two parameters of acid fracturing, conductivity and effective acid-etched fracture length, were obtained by numerical simulation with commercial software Fracpro PT. Based on the laboratory studies, the acid fracturing technology was applied in the field, and the production of well increased by 1.7 times after stimulation.

Controllable function equation of silicone elastic materials through MATLAB and its tribological properties

The precise controllability of the elastic abrasive tool has always been a major problem in the engineering field. Based on the previous experiments, the objectives and scope of the research fit the compression controllability function equation of the elastic abrasive tool based on MATLAB software. The compression mechanics characteristics of elastic abrasives were analyzed. The reliability of the equations and the tribological properties of elastic abrasives were studied. The results show that the cell size and density of the foamed composite have a great influence on the compressive mechanical properties and tribological properties of the material. The thickness of the matrix among the holes will determine the elastic resistance of the material and the surface quality of the workpiece to be processed.

Test and numerical investigations on the spatial mechanics characteristics of extra-wide concrete self-anchored suspension bridge during construction

This work is aimed at studying the mechanics characteristics of the self-anchored suspension bridge with extra-wide concrete girder during girder erection and system transformation. First, the determination and implementation processes of reasonable completion state were introduced briefly, taking the Hunan Road Bridge as the background project, which is the widest concrete self-anchored suspension bridge in China currently. Then, the ANSYS beam-type finite element model and field monitoring data were integrated to investigate the cable system evolutions during system transformation. Finally, the global refined finite element model was established using solid element to consider the shear lag effects in extra-wide girder. The measured data show that the cable displacements in tensioned domains were characterized by weak coherence and contraflexure characteristics. The longitudinal and transverse stresses of extra-wide girder distributed unevenly along transverse direction. The maximum shear lag coefficients of girder at completion state reached to 1.3. Moreover, small transverse compressive stress, or even the transverse tensile stress reaching to 1.80 MPa, appeared in the top plate segments. The measures including the arrangement optimization of transverse prestressed tendons and monitoring point redistribution were given. The research can provide references for the structural designing and safety control of the similar bridges.