IPR CURVE CALCULATING FOR A WELL PRODUCING BY INTERMITTENT GAS-LIFT METHOD

Master degree thesis (Mr i Z., 2009) shows the detailed procedure of calculating inflow performance curve for intermittent gas lift, based entirely on the data measured at surface. This article explains the detailed approach of the mentioned research and the essence of the results and observations acquired during the study. To evaluate the proposed method of calculating the average bottom hole flowing pressure (BHFP) as the key parameter of inflow performance calculation, downhole pressure surveys have been conducted in three producing wells at androvac and Bilogora oil fields: androvac-75 , Bilogora-52 and androvac-34. Absolute difference between measured and calculated values of average BHFP for first two wells was p=0,64 bar and p=0,06 bar while calculated relative error was r=0,072 and r=0,0038 respectively. Due to gas-lift valve malfunction in well androvac-34, noticed during downhole pressure survey, value of calculated BHFP cannot be considered correct to compare with measured value. Based on the measured data the information have been revealed about actual values of a certain intermittent gas lift parameters that are usually assumed based on experience gained values or are calculated using empirical equations given in literature. The significant difference has been noticed for a parameter t2. The length of a minimum pressure period for which the measured values were in range of 10,74 min up to 16 min, while empirical equation gives values in the range of 1,23 min up to 1,75 min. Based on measured values of above mentioned parameter a new empirical equation has been established.