Study On Early Kick Detection Based On The Measured Information LWD And APWD In Deepwater Drilling

Blowout is the most dangerous safety accident during deep water drilling and completion engineering.Gas invasion normally holds a characteristics of concealing and cannot be found effectively.Therefore,gas invasion may cause the serious blowout.The application of early kick detection technology can effectively avoid the occurrence of this kind of accident.The earlier the gas invasion is found,the longer the security response time window is,and much easier to avoid well blowout accidents by well drilling operation.Due to the special process and environmental conditions of deep water drilling,conventional kick detection technology cannot meet the requirements of early kick detection in deep water.This paper mainly focuses on the gas invasion response characteristics of the key measurement parameters of the down hole drilling tools LWD(Logging While Drilling)and APWD(Annulus Pressure While Drilling),which is revealed the law of variation of the overflow characteristic parameters caused by gas invasion.Based on this,a comprehensive discriminant method for early kick detection of deep water is constructed.Through the simulation experiment of gas invasion,we obtain the variation characteristics and laws of the LWD Gamma Ray under different gas invasion conditions.Experimental results show that the value of LWD Gamma Ray increases with the increase of the volume fraction of the annular gas.Based on response of LWD Gamma Ray which gas invasion occurred,a calibration model of LWD Gamma Ray with gas is established.We deduce the prediction model of the volume fraction of down hole gas.Based on this,a prediction method for the volume fraction of down hole gas is given based on LWD Gamma Ray.By comparing the gas volume fraction of the experimental results and theoretical model prediction results,the two results are in a good agreement.The mean error is less than 8%.A set of gas invasion simulation test equipment is innovated and is used to study the variation law of LWD resistivity when gas intrusion into the wellbore at different gas injection rates.Through the experimental study,gas invasion response characteristics and the variation law of LWD resistivity and mud resistivity are obtained.The correlations are obtained to describe relationships between gas volume fraction and dimensionless LWD resistivity,gas volume fraction and dimensionless mud resistivity.In addition,the relative average error of the fitting formula and the test data is less than 5%.With LWD resistivity measuring tools,the pulsation and distribution characteristics of the instantaneous LWD resistivity are analyzed.Furthermore,we can identify the annular flow pattern at the bottom of the well.We consider the water shock effect at the initial stage of gas invasion.In this paper,we have established a mathematical model and solution method to accurately describe the APWD annulus pressure changes after gas intrusion.In addition,the full-scale experimental well is used to verify the accuracy of the mathematical model and solution method.Combined with a specific example,we analyze the annular pressure of APWD after gas intrusion.Based on this,we propose a change pattern of APWD measurements that can be used for early kick detection.The application conditions of the method are determined.By this method,the volume of gas invasion are calculated and the warning volume of the gas invasion is set.The results show that the volume of the gas invasion and warning volume of the gas invasion are significantly smaller than those of the conventional overflow monitoring method.A comprehensive discriminant method is established for early kick detection in deep water based on pattern recognition and analytic hierarchy process.This method is used to simulate the early stage of gas invasion in a deep water gas well.Compared with the conventional mud pond increment method,the occurrence of gas invasion can be monitored 10 minutes in advance.Compared with the early detection of riser gas invasion,the occurrence of gas invasion can be monitored 6 minutes in advance.In summary,the method not only detects gas invasion before the gas enters the riser,but provides technical support for the calculation of well killing.Based on the theory of comprehensive discrimination method of early detection of deep water overflow,a set of early-monitoring device for deep water overflow was developed by the field test and practical application of a high-temperature and high-pressure well in the South China Sea.Using this method,the accuracy of software and device for overflow early detection can reach 100%.It takes 7-12 minutes earlier than the use of conventional overflow monitoring method to discovery the occurrence of overflow.