Search Results (2)

The Central Anticline Belt of the Xihu Sag is one of the structural units with the most abundant natural gas in the East China Sea Shelf Basin. However, there are significant differences among the anticline units in terms of the scale of natural gas enrichment, occurrence horizons, types of gas reservoirs, accumulation processes, and gas-bearing properties of different strata, which influence the optimization of exploration zones and the orientation of exploration in deep-buried areas. This study conducted a comprehensive analysis in terms of the structural evolution, fault activity, hydrocarbon charging stages, and process of hydrocarbon accumulation. It clarifies that (1) the preservation condition is one of the core factors for the differential enrichment of natural gas in the Central Anticline Belt. Under the background of differential compression of the Longjing Movement, late-stage and E-W-trending faults are commonly developed in the anticline cores of the strong compression area in the south, which damage the effectiveness of traps, resulting in a large amount of natural gas escaping and being locally adjusted and accumulated in shallow effective traps. The gas reservoirs show the characteristics of multiple accumulation horizons and a small scale. In the moderately strong compression area in the north, the E-W-trending faults have weak activities and shallow incision horizons. The original gas reservoirs are not damaged, and the structures are fully filled. (2) The coupling between faults and sand bodies determines the degree of oil and gas enrichment. In the weakly compressed area in the west, late-stage E-W-trending faults are not developed, and the preservation conditions are good. The main controlled faults on the flanks of the anticline are highly active, and the coupling degree between faults and sand bodies is good, resulting in a high gas saturation. However, the transport capacity in the anticline cores is relatively poor, with a low gas saturation. (3) The differences in the paleo-structural characteristics affect the degree of oil and gas enrichment. The paleo-structures formed before the Longjing Movement provided favorable conditions for the early convergence of oil and gas. Natural gas has the characteristics of multi-stage charging, and the deep gas reservoirs have higher gas saturation than the shallow ones. On this basis, this study proposed two natural gas accumulation processes developed in the Central Anticline Belt of the Xihu Sag under the background of differential compression. One is where the hydrocarbon convergence occurs first and then oil and gas transport and accumulate into the reservoirs; the other one is where the hydrocarbon convergence and accumulation occur simultaneously, followed by gas adjustment. This paper also concludes three differential accumulation models: the local enrichment and accumulation model of gas in the strongly compressed zone, the integrated enrichment and accumulation model in the medium-strongly compressed zone, and the fault–sand coupling accumulation model in the weakly compressed zone. The results of this research have great significance for the subsequent exploration, hydrocarbon enrichment style analysis, and further strategy in the deep-buried, tight to low-permeable reservoirs in ocean exploration areas. Full article

To improve the wet clutch engagement quality, which is widely used in agricultural machinery, the oil filling control strategy of a wet clutch is studied based on the method of simulation and experiment in detail in this paper. Firstly, this paper carries out the dynamic analysis of the wet clutch engagement process, establishes the mathematical model of the mechanical domain and the hydraulic domain of the hydraulic execution system, and designs the backstepping oil pressure controller. The controllability of the output oil pressure of the clutch hydraulic actuator is verified on the joint simulation platform of Matlab/Simulink (Version R2017b, MathWorks, Natick, MA, USA) and AMESim (Version 2019.1, Simcenter Amesim, Siemens Digital Industries Softwares, Berlin&Munuch, Germany). Then, this paper analyzes the clutch engagement process, extracts five factors affecting the oil filling process, and selects four clutch engagement quality evaluation indexes. An amount of 50 groups of experiments are carried out on the wet clutch oil filling test simulation platform built by SimulationX (Version 3.8, ESI ITI GmbH, Dresden, Germany). The response surface method (RSM) and stepwise regression analysis method are used to explore the mathematical models of the quality evaluation index and influencing factors of the oil filling process. Through 15 groups of random tests, the prediction accuracy of the stepwise regression model and the RSM model of each index is compared, and the models with high accuracy are selected to establish the comprehensive prediction mathematical model of clutch engagement quality, combined with the variance weight method. Finally, according to the working condition of the 3 MPa oil filling pressure studied in this paper, the optimal oil filling control strategy is obtained by the proposed clutch engagement quality prediction model. Under the target condition, when the oil filling rate of stage 1 is the highest and the proportion of phase 1’s duration to the total oil filling time is 69.65%, the oil filling rate of stage 2 is the lowest and the proportion of phase 2’s duration to the total oil filling time is 21.85%, and the proportion of phase 3’s duration to the total oil filling time is 8.51%, the engagement quality of wet clutch is the best. The research method of wet clutch optimal oil filling control strategy proposed in this paper provides a reliable method for the ride comfort research of agricultural machinery and clutch control. Full article