WAVELET TRANSFORM THRESHOLD NOISE REDUCTION METHODS IN THE OIL PIPELINE LEAKAGE MONITORING AND POSITIONING SYSTEM

This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principles, features and design steps of the threshold method. Rigrsure, heursure, sqtwolog and minimization four kinds of threshold selection method are compared qualitatively, and quantitatively. The wavelet analysis toolbox of MATLAB helps to realize the computer simulation of the signal noise reduction. The graphics and calculated standard deviation of the various threshold noise reductions show that, when dealing with the actual pressure signal of the oil pipeline leakage, sqtwolog threshold selection method can effectively remove the noise. Aiming to the pressure signal of the oil pipeline leakage, the best choice is the wavelet threshold noise reduction with sqtwolog threshold. The leakage point is close to the actual position, with the relative error of less than 1%.

Research on Oil Pipeline Leak Detection and Location system

Because pipeline has large pipe diameter, large throughout and high pressure, once pipeline leakage accident happens, the damage is quite serious. In addition, pipeline leakage accident caused by man-made drilling oil stolen every year results in huge economic losses on oilfield. Therefore, a real-time and accurate pipeline leak detection and location system not only can effectively decrease leakage loss and reduce the waste of manpower and material resources in patrolling work, but also is conductive to the management of oil pipeline and improvement of economic efficiency of enterprise. The paper determines leak detection and location project giving priority to negative pressure wave and supplemented by flow parameter analysis. The method not only can judge the accidence of leakage timely and accurately, but also can effectively avoid leakage false alarm caused by start or stop pumps in pipeline.

Petroleum Charging and Leakage in the BZ25-1 Field, Bohai Bay Basin

This paper discusses origin and charging histories of the Bozhong （渤中） 25-1 field （BZ25-1） in the Bozhong sub-basin, Bohai （渤海） Bay basin. Petroleum is contained in both Paleogene and Neogene reservoirs in the BZ25-1 field. The origin of the field was studied using biomarker distri-butions for 61 source rock samples and 34 oil samples. Oil in the Paleogene reservoirs was derived from the third member （Es3, 43.0-38.0 Ma in age） of the Eocene Shahejie （沙河街） Formation, whereas oil in the Neogene reservoirs was a mixtures of oil generated from the third member and the first member （Es1, 35.8-32.8 Ma） of the Eocene Shahejie Formation. Charging of the shallow Neogene reservoirs was dynamic, probably ongoing, which was a combined result of the existence of active source rocks, the development of overpressure and the fault reactivation since about 5.1 Ma. On the contrary, the deep Paleogene reservoirs experienced intensive oil leakage as indicated by the high GOI （grains-containing-oil-inclusions） values （up to 30%） for samples below the present-day oil-water con-tact. Part of the oil that leaked from the Paleogene reservoirs re-accumulated in the shallow Neogene reservoirs. The variation of oil origins within the BZ25-1 field, and the dynamic petroleum charging into the shallow Neogene reservoirs and leakage from the deep Paleogene reservoirs have important implications for petroleum exploration.