油轮空舱鉴定影响因素研究

由于当前技术水平的局限,国内外大型油轮装货前卸货后的底油量始终无法较为准确的测定,从而直接影响了装货和卸货的船测数据准确性。近年来,在舟山口岸进行清洗舱作业的大型油轮逐渐增加,根据海关监管的需要,船方委托我公司对所有外籍油轮最终清洗出来的油污水、含油量、油泥等进行数重量鉴定。通过对这些数据进行收集分析,发现实际清洗出来的油品数量与在日常的鉴定工作中对油轮的底油进行计量所得的数量有一定的差别。本文通过对影响底油量的一些因素逐一进行数据分析,从中得到一些经验和规律,以供鉴定人员在日常的船舱计量工作中作为参考。

A novel method for predicting breakthrough time of horizontal wells in bottom water reservoirs

Dimensional analysis and numerical simulations were carried out to research prediction method of breakthrough time of horizontal wells in bottom water reservoir. Four dimensionless independent variables and dimensionless time were derived from 10 influencing factors of the problem by using dimensional analysis. Simulations of horizontal well in reservoir with bottom water were run to find the prediction correlation. A general and concise functional relationship for predicting breakthrough time was established based on simulation results and theoretical analysis. The breakthrough time of one conceptual model predicted by the correlation is very close to the result by Eclipse with less than 2% error. The practical breakthrough time of one well in Helder oilfield is 10 d, and the predicted results by the method is 11.2 d, which is more accurate than the analytical result. Case study indicates that the method could predict breakthrough time of horizontal well under different reservoir conditions accurately. For its university and ease of use, the method is suitable for quick prediction of breakthrough time.

发动机机油压力过低的原因及预防

发动机在工作时，各运动零件的接触面，如活塞、活塞环与气缸壁、曲轴与主轴承等之间以很高的速度作相对运动而发生摩擦。如果发动机的机油压力过低，机件得不到充分的润滑，会使工作表面发热和磨损，降低机件的使用寿命，影响发动机的动力性和经济性。引起发动机机油压力过低的原因有以下几种。