关键词: 主控因素, 大数据, 数据清洗, 产水, 消元法, 多因素分析

Abstract: It is well known that water production is the main factor leading to low production and low efficiency of gas wells. However， due to the lack of understanding of the main controlling factors of water production，applying the conventional drainage gas production method is always of low efficiency. In order to comprehensively study the main controlling factors of water production，the cocoon stripping optimization algorithm by big data analysis is introduced to firstly establish a big data sample library for factors that may affect water production，including geological，engineering，drainage and production factors；secondly，all the data is cleaned to eliminate invalid data. After that，the single factor analysis is carried out to determine the positive and negative relationship of each factor；then，multifactor analysis is conducted to find out the main controlling factors affecting water production in tight gas wells. Finally，39 main controlling factors are found out by using elimination method and the main control equation of water production is established to define the effect of each factor on water production. The study shows that：the main factors that greatly affect water production are producible porosity and total porosity identified by logging，gas testing and production casing pressure，clay content，etc. In order to avoid the impact of water production on gas production in the later stage，the reservoir sections with larger producible porosity，larger total porosity and lower clay content are preferred for fracturing. Meanwhile，the production scheme shall be implemented in the production process to avoid excessive pressure difference which can aggravate formation water production，so as to provide a basis for taking effective treatment measures for water-producing gas well in the later stage. 

Key words: main controlling factors, big data, data cleaning, water production, elimination method, multi-factor analysis