A New Method For Measuring Porosity Of Dense Rocks By Air Drilling

Air drilling afraid of water, therefore in the process of drilling it needs to monitor the humidity value of recycle gas all the time. But no one has systematic researched and interpreted the data of recycle gas humidity which collected from drilling site, and the long-running precise measurement of the humidity is recognized a world-class challenge, also a research challenge of this method. So the recycle gas humidity data often cannot be fully used. This paper researched the reason of humidity data change and the method of humidity monitoring, put forward the new method of measuring the porosity by monitor the change of recycle gas humidity. This method can monitor the trend of porosity change while drilling, provide engineering technical personnel a new way to understand the stratum information. The advantage of this method is low cost and can realize measurement while drilling. The disadvantage of this approach is not accurate enough easily affected by various factors.The method of debris measurement means calculate the original porosity of formation rocks by measuring the porosity of rock debris. The accuracy of this measured rock porosity method is higher than the humidity method, but we cannot achieve real-time measurement because this measuring method is trouble.So we support to combine the two methods to calculate rock porosity. Humidity monitoring can point the layer which may have great changes, we can increase the debris measurement frequent, at the same time also can give the porosity change trend of blind area of debris measuring method, so that you can get the continuous relatively accurate information about the formation porosity.In this paper the innovation point is to combine the debris measuring method with the humidity monitoring method, mutual complement each other. Not only make full use of the data obtained by field measurement recycle gas humidity, but also provides a new method for the site understanding formation porosity situation while drilling. This paper not only puts forward a new measuring method of formation rock porosity but also do a lot theoretical evidence and relevant experiments. Also design the related measuring equipment analyzed and explain some field data, laid the foundation for the future on-site validation and application.This article not only put forward the new measurement method of porosity, but also have detailed understanding of air changes in the whole cycle during the air drilling. But with the limitation of time, we cannot carry on the field validation and trial, therefore we hope the later researchers can continue deeper study on this field.