A Novel Approach to Evaluate Deliverability of Gas Wells with Pressure Fluctuation

Abstract

Majority of gas fields in Tarim Basin are HPHT (high-pressure/high temperature) reservoirs with buried depth more than 5000m. The special geological conditions made it a challenge for underground well testing due to safety issues. Additionally, wellhead pressure fluctuation is widely existed both from geological and engineering factors, including sand production, well casing integrity problems, contamination of downhole fracturing fluid and wax deposition in wellbore etc. Traditional deliverability evaluation method which relies on underground well testing is greatly limited as it is not capable of reflecting the dynamic change of gas well deliverability due to abnormal wellhead pressure fluctuation. In this study, a new approach is proposed to evaluate the deliverability of these kind of wells using dynamic data from wellheads. An apparent and a potential deliverability curves are based on binomial deliverability equation are established individually according to whether the additional skin caused by wellbore blockage is taken into consideration. The variation characteristic of gas well deliverability is obtained by comparison of potential and apparent absolute open flow. Finally, field studies of Dina abnormal wells are performed to verify the accuracy of the method. Deliverability analysis show that the new approach has a great advantage in evaluating the production potential of wells with pressure fluctuation, and furtherly provides the criteria for wellbore management.