Sand Production Determined from Noise Measurements

Abstract

A method has been developed for using a logging tool in wells with sand problems to develop information on (1) producing rates above which sand production occurs, (2) the location of the sand-producing interval in a zone, and (3) the flow rate contributions of various segments of a perforated interval. Introduction In any area subject to sand production problems, it is desirable to know what production rate will precipitate sand movement and at what formation depth precipitate sand movement and at what formation depth the sand is being produced. These questions are particularly important in multiple-completion gas particularly important in multiple-completion gas wells in which produced sand from an upper formation can strike the tubing that reaches to the lower formation. Tubing failure often occurs in such blast zones unless some preventive measure is taken, such as (1) using blast-resistant material in the tubing string, (2) using some form of sand control, or (3) restricting production rate. Knowledge of the sand-producing tendencies of the formation can be helpful in applying any of these measures. Theoretical Considerations Produced fluids striking tubing will generate noise. Produced fluids striking tubing will generate noise. Sand carried in fluid moving at a given velocity will contribute additional noise. A well log can be made that reflects generated noise per unit of time recorded as a function of production rate and depth. Relation Between Total Noise and Production Rate We assume that the generated noise is proportional to the kinetic energy of the materials produced into the wellbore per unit of time. Then(1) However, (2) and (3) Substituting Eqs. 2 and 3 into Eq. 1 gives (4) For a given toad productive interval in a well, A and L can be included with the other constants in a new constant, C2. Thus,(5) Taking the logarithm of the terms on each side of Eq. 5, then taking the derivative of each term with respect to log q, gives(6) Eq. 6 can be used to define the fluid production rate at which sand production begins. A plot of thei logarithm of Nd vs the logarithm of q for ad=1 single-phase fluid at two levels of q results in a straight line with a slope of 3 if no sand is produced. JPT P. 803