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顾心阳 金威 【摘要】 乌克兰危机短期内对中国拓展在海外的利益是不利的。中国在乌克兰拥有广泛的利益，但这些利益正在或即将因乌克兰危机受到影响。对于中国在乌克兰的利益，本次危机主要带来了负面影响。而对于中国在其他国家的利益，本次危机不光带来了消极影响，也有着积极影响。乌克兰危机仍在进行中，短期内似乎无法解决，如何衡量利弊得失，需要时间来证明。而中国如何利用这次危机达到获益最大、损失最小，实现利益的最大化，需要决策者的智慧。此次乌克兰危机对中国在海外谋求自身利益的影响也促使我们思考今后应该如何应对类似事件、保护在海外的利益。政党轮替、党派冲突是造成乌克兰等国动荡的主要因素，这提醒我们今后在这些国家拓展利益需要谨慎，如果一定要在这些国家拓展利益，不但需要与现任执政者搞好关系，同时也需要与反对派搞好关系。 The Ukrainian crisis is harmful to China’s overseas interests from a short term perspective. A wide range of Chinese interests in Ukraine are facing challenges due to the Ukrainian crisis. The impact of the Ukrainian crisis on China’s interests in Ukraine is mainly negative whereas the impact on China’s interests in other foreign countries is both negative and positive. The Ukrainian crisis is still in progress, and it does not seem to be reaching a resolution in the near future. Only time will tell what the ultimate impact will be. How China utilizes the crisis to maximize its gains and minimize its losses will test the wisdom of decision makers. The Ukrainian crisis’s impact on China’s overseas interests prompts us to consider how to deal with similar events and protect overseas interests. Rotation of ruling parties and the partisan conflicts are the major factors of turmoil occurring in Ukraine and other countries which reminds us that an expansion of interests in these countries needs to be prudent in the future. If China has to do so, it is necessary to build good relationships both with the ruling party and the opposition.

High stress is the main reason for high frequency of rock burst in deep coal mines. Backfilling mining serves as an effective method to control roof strata movement, alleviate the degree of stress concentration, and reduce the failure of surrounding rock and the risk of rock burst. To evaluate the controlling ability of the backfilling on mining stress in the gob area, the 1123 longwall panel of the Gucheng mine is taken as the project background. Theoretical analysis, laboratory test and field measurement are used to study the mining-induced stress distribution in the backfilling longwall face, and to reveal the feedback mechanism between the front abutment stress and bearing capacity of the backfilling body, helping to determine the backfilling rate of coal burst mine. The results show that the backfilling ratio in the early stage is lower than 80%, the subsidence of hard roof is serious, the influence area of front abutment stress is more than 30 m, and the degree of stress concentration reaches 1.5. The influence area and concentration degree of mining-induced stress in the fault affected area increase to 60 m and 1.65, respectively. Surrounding rock instability phenomenon, such as rib spalling and roof fall, happens frequently. The whole dynamic evolution characteristics of bearing stress in the backfilling body is measured. The stress distribution curve is divided into five stages, namely rapid decrease, transient stabilization, rapid increase, slow decrease, and secondary stabilization. The stabilization values of the bearing stress in the upper, middle, and lower regions of the gob area under the condition of low backfilling ratio are 1.5, 5.2 and 2.5 MPa, respectively. The backfilling body in the gob area is divided into non-sufficiently compacted zones and sufficiently compacted zones, and the continuous subsidence model of the hard roof under the support of the backfilling body is constructed, and the “ʅ” type subsidence curve of the hard roof is obtained, and the range of the insufficiently compacted area decreases approximately linearly with the backfilling ratio. The test obtains the evolution curves of elastic modulus and uniaxial compressive strength of the back-filling body with time. By combining with the roof subsidence curve and face advance speed, the distribution curve of mining-induced stress in the whole area of the longwall face is obtained. Negative exponential relationship is established for the backfilling rate and the afront abutment stress, which reveals the reverse feedback mechanism between them. Quantitative assessment on the load reduction and burst prevention effect of backfilling mining is realized. The trinity enhancement measures for improving the backfilling ratio of the gob area are proposed, which raises the backfilling ratio of the 1123 working face to more than 90%. The bearing capacity of the backfilling body is strengthened. The trinity measures reduce the separation space under the hard roof to 50 mm. The stress concentration coefficient decreases to 1.3. Correspondingly, the controlling effect of the surrounding rock of the longwall panel is significantly improved.

Considering the phase behaviors in condensate gas reservoirs and the oil-gas two-phase linear flow and boundary-dominated flow in the reservoir, a method for predicting the relationship between oil saturation and pressure in the full-path of tight condensate gas well is proposed, and a model for predicting the transient production from tight condensate gas wells with multiphase flow is established. The research indicates that the relationship curve between condensate oil saturation and pressure is crucial for calculating the pseudo-pressure. In the early stage of production or in areas far from the wellbore with high reservoir pressure, the condensate oil saturation can be calculated using early-stage production dynamic data through material balance models. In the late stage of production or in areas close to the wellbore with low reservoir pressure, the condensate oil saturation can be calculated using the data of constant composition expansion test. In the middle stages of production or when reservoir pressure is at an intermediate level, the data obtained from the previous two stages can be interpolated to form a complete full-path relationship curve between oil saturation and pressure. Through simulation and field application, the new method is verified to be reliable and practical. It can be applied for prediction of middle-stage and late-stage production of tight condensate gas wells and assessment of single-well recoverable reserves.