Numerous studies have addressed the effect of grain size of materials on the overall penetrating performance of warheads. However, the use of the forging process to illustrate the grain heat-treatment refining technology has not been reported. In this experiment, the grain size of copper was observed and evaluated during the main processes of preparing copper shaped charge liners using the die forging process. Through this study, the evolution law for the structure of copper shaped charge liners was examined. In the as-cast condition, the grains of the copper ingots were mostly evenly distributed large flaky equiaxed crystal. Pre-forging and die forging make the grains appear more like strips. After the recrystallization heat treatment, the grain size of the copper shaped charge liner was refined and more uniform. Using these results, this study presents an evolution curve for copper shaped charge liners prepared using the forging process. The results can be used as a technical reference to solve the problem of grain size deviation in the production process of copper shaped charge liners.

In order to study the impact performance of 685 armored steel with different mischmetal content, the impact performance of the steel at room temperature and -40°C was tested, and the impact fracture morphology and microstructure were observed and analyzed. The results show that the addition of mixed rare earth La-Ce to the test steel improves the tempered martensite structure and refines the austenite grains. At the same time, the inclusions in the steel are modified, and the elongated MnS inclusions are modified. It is a spherical composite rare earth inclusion, and the size of the inclusion is reduced from 6 μ m to 2 μ m. Compared with the test steel without rare earth, the room temperature impact performance of the mixed rare earth test steel and the -40 °C low temperature impact performance are improved. When the La-Ce content is 102 × 10−6, the room temperature impact energy of the protective steel increases by 24.5%, and the low temperature impact energy at -40 °C increases by 17. 4%. The results of the shooting test showed that the protection level of rare earth-containing armored steel reached NATO Level 2.

Thermoplastic composite pipes (TCPs) are becoming the ideal substitute for traditional steel pipe due to its superiorities including light weight and corrosive resistance. The cross-section of TCPs consists of an inner liner, a laminate layer, and an outer jacket. The laminate layer is made of multi-plies of helically wound continuous fibre reinforced unidirectional tape. In the present study, a three-dimensional (3D) theoretical model and a 3D finite element model were developed to analyse the stress state of a TCP under internal pressure. With a selected failure criterion for composite laminate, the ultimate burst pressure of a TCP can be predicted. By comparing the predicted burst pressure with the experimental results, several commonly used failure criteria were compared in terms of their accuracy.

As the search for petroleum has moved into the high-pressure/high-temperature (HP/HT) environment, the well control problems have continued to increase in complexity due to the small pressure margins and the large temperature-driven variations of mud properties often seen. Recently in western China, a major kick was encountered while drilling to 7874 m with 16-ppg water-based mud in an HP/HT well. Killing of the well was attempted but was not successful. After that, the drillstring broke near the top of wellbore. As a contingency action, the operator abandoned the plan for further killing and put the well into production through diverting the kick to the production pipeline. Many unknowns, which were unsolvable by conventional perceptions, were still intriguing the operator and might be issues in further drilling operations in this field. These unknowns include: (1) Why was the well pressure constant before the gas reached the wellhead while the well was shut-in for almost 2 days? (2) Where was the gas top during shut-in? (3) Why did the killing attempt fail? (4) What killing parameters should have been used in the killing attempt? To address these unknowns and provide solid guidance for further drilling operations, simulation of the gas kick development and well killing was conducted using a dynamic hydraulic and well control simulator powered by transient multiphase flow model. Through integration of existing well and reservoir data, the dynamic simulation was able to history match the observed wellhead pressure, casing pressure during the shut-in, and killing operations. The simulation showed that the killing pump rate was not adequate to kill this well for the given gas kick in the wellbore. The dynamic simulations successfully revealed the reason for the gas suspension in the wellbore while shut-in, predicted the gas top, and identified the required pumping rate for a success killing. The simulation also disclosed the root cause of the drillstring failure. This case study highlights the importance of dynamic simulation during the well engineering design and before any attempt of well killing to improve chance of success for well control and safety of drilling operations.