Design of the Down Hole Instruments of Multiplexed Logging System and Research on the Data Compression of DHV Logging System

Several logging instruments can be flexibly assembled in a Multiplexed Logging System, through which many kinds of petroleum logging data can be acquire when it is put in petroleum wells. This technique can increase greatly the efficiency and reduce the cost of petroleum logging. DHV is an another applicable technique of logging. It is a kind of optics television that is used in the field of logging. Pictures, which show the exactly conditions in well, can be acquired by a down hole camera and transmitted to the devices on the ground. These pictures are displayed lively, accurately and vividly on the screen of a monitor on the ground. The design of the down hole instruments of a Multiplexed Logging System are introduced in this thesis. Four instruments include temperature measurement device and nature gamma measurement device and so on are concentrated. In this system, signal can be transmitted in the form of analog or digital data. The two kinds of system are both explained. Another kind of Multiplexed Logging System produced by other company is analyzed, which is expected to help us in our future work. Another subject in this thesis is the data compression of DHV logging system. There are two vital difficulties in the system. One is the extreme condition in the petroleum wells. Since the temperature and pressure are very high and there is no light in the well, pictures are hardly gained through a camera. The other difficulty is that the transmission over a logging cable is slow, but the data of pictures are very large. The algorithm based on DCT is simple and easy to be implemented. The way to implement this algorithm has been presented in detail in the thesis.

Alternate abstract:

多参数组合测井系统具有一次下井，就能够获取多种测井参数的优点。根据需要，多参数组合测井系统可以灵活地组合多种测井仪器，它的应用可以显著地提高测井的效率，减少测井的成本，有较高的实用价值。DHV测井系统是另外一种非常实用的测井手段，它实际上是光学电视系统在测井中的应用。DHV系统能通过井下摄像机把油井内部的情况拍摄下来，并把得到的图像传送到地面系统，通过地面的显示设备，可以实时、准确、直观地显示井内的情况，是一种新型的测井手段。本文介绍了多参数组合测井仪井下仪器的设计原理，其中重点介绍了测温仪、自然伽马仪等四种仪器的设计方法。多参数组合测井仪包括模拟传输方式和数字传输方式两种，论文分别介绍了它们的设计思路。论文还分析了其它公司设计的一些组合测井仪器，希望它们能对我们的工作起到一定的借鉴作用。论文的另一部分内容是DHV测井系统中图像数据的压缩。DHV测井首先要解决两个问题，一是在无自然光、高温、高压环境下的摄像问题；二是在单芯测井电缆中实时传输测井图像的问题。图像数据量较大，但单芯测井电缆的传输速率是非常有限的。在图像传输实时性要求不高的情况下，基于DCT基础上的图像压缩具有算法简单，容易实现的优点。本文较详细地介绍了这种算法的实现过程。