| During the oil drilling operations it is essential to acquire lithologic information which is needed to establish formation top,evaluate reservoir,predict formations to be penetrated,and guarantee normal performance of drilling operations.However,due to the development of drilling technology and production speed requirements,the drilling construction process using PDC bit + screw in Rumaila Oilfield,it caused the wellhead to return with less and fine cuttings.So the traditional cuttings logging method is difficult to accurately identify lithology,divide the formations and build the sections.Propose more problems in understanding the reservoir,accurate to interpret and evaluate the reservoir,forecast engineering accidents.Based on the technology status and development trend at home and abroad,combined with the situation in Iraq and special geological characteristics of Rumaila Oilfield,a series of studies have been conducted on multidisciplinary related knowledge such as comprehensive application of petroleum geology and drilling technology.1.Against the problems of cuttings identification for PDC bit + screw drill assembly,based on traditional cuttings logging method,use a combination of different mesh sieves to clean the cuttings to keep more real cuttings,then use an an optical digital microscope to generate high resolution photos,at last use photographs to accurately determine lithology.This method has the characteristics of high accuracy,easy to operate,low equipment use and maintenance costs.More detailed and definite definition of the principle of division of each formation.Improve the coincidence rate of the profile in well site.2.In addition,the article analyzes the influencing factors of gas logging data in the Rumaila Oilfield.By analyzing the different gas logging curve shape characteristics and the results of oil and gas show,set a method for using gas curve shape to interpret and evaluate the Mishrif and Zubair formation.Against principle of interpretation and limitation of using Pixler chart to interpret and evaluate the reservoir,we analyzed the gas logging data and the characteristic of Pixler chart in the Rumaila Oilfield,we can know the range of gas ratio of C1/C2 in Mishrif and Zubair formation and the characteristics of Pixler chart curve shape.Improved the applicability of the Pixar chart interpretation method in Rumaila Oilfield.3.At last we also explored the research of engineering logging in Rumaila Oilfield.Passing on the engineering accident data and typical accident of Rumaila oilfield in recent years,lost circulation and stuck pipes(casing)caused by geological(formation and lithology)factors account for 97.1% of all accidents,lost circulation occurred mainly in Dammam and Hartha formation,the rate of South Rumaila higher than North Rumaila.There are 34 out of 35 wells lost circulation in Dammam formation of South Rumaila.And through the analysis of typical accidents fully affirmed this conclusion. |
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