Securing the Future: Gas Well Deliquification Strategy for Mature Gas Wells in Tripura

Abstract

Abstract Objectives / Scope In a lifespan of a gas well multiphase flow regime keeps changing. When gas rate falls below critical rate, gas well loads up, significant reduction in gas rate occurs and eventually well ceases to flow. Tripura Asset is operating nearly 100 wells and most of them experience liquid loading in their production life, leading to loss of recovery. Many wells have experienced a sharp decline in production due to liquid loading. The paper highlights integrated production modelling approach adopted to identify liquid loading in wells and successful application of gas well deliquification techniques for optimising production and improving recoveries in Tripura. Methods, Procedures, Process All the 100 plus wells have been modelled in PIPESIM, an integrated production modelling software to identify propensity of liquid loading. Flowing tubing head pressure (FTHP) and casing head pressure (CHP) trends were captured in well monitoring sheets. Flowing gradient survey, variation in FTHP and CHP in union with the results of PIPESIM were used to identify liquid loading tendency in wells. A network model was created for determining the reserve gains on application of deliquification technique. Based on analysis wells were categorised as free from liquid loading, loaded in casing not in tubing and fully loaded. A multidisciplinary approach was adopted to identify and evaluate long and short-term deliquification measures to be adopted for deliquification and get maximum ultimate gas recovery from the wells – use of nitrogen, activation, smaller tubing, plunger, sucker rod pump (SRP) and progressive cavity pump (PCP). Results, Observations, Conclusions System analysis indicated about 25 wells, which required frequent activation, were completely liquid loaded. Only 5-6 wells were free from liquid loading. Implementation of short-term measures as activation by beaning up the well and injecting of nitrogen in identified wells has prevented well from ceasing. After an extensive study one well was identified and completed on pilot basis on 2 3/8″ tubing, with shoe run upto perforation. The technique has lifted the well out of liquid loading region. Positive displacement pump, with pump placed below the perforation, have been used for reviving 5 ceased liquid loaded wells and for increasing production from 1 liquid loaded well. Of the 6 wells – 5 have been completed on SRP and 1 on PCP, which has ensured revival of 41 MMSCM of gas. Plunger lift, a system that removes liquid slugs in gas wells using wells own energy has resulted in revival of 65 MMSCM of gas. The system has been implemented in 25 wells with substantial gains in 15 wells. Plunger lift optimisation being done on regular basis, based on changing liquid gas ratio, changes in THP and CHP has ensured optimal plunger performance. The pilot approach of putting in place continuous deliquification techniques has not only helped in enhancing production from the existing liquid loaded well but has also opened up new avenues to revive wells ceased due to liquid loading. During initial assessment of 100wells, ~70 wells are potential deliq candidates that can add potentially ~312 MMSCM of reserves. Novel/Additive Information The adopted approach has been useful in formulating a novel strategy to minimize the effect of liquid loading in wells of Tripura. Results of pilot implementation has helped Asset to understand and devise deliquification workflow to be adopted specific to the reservoir condition and well production parameters.