Solutions for Sucker Rod Pump Systems in Sandy Conditions
Research output: Thesis › Master's Thesis › Research
The aim of this thesis is to analyse problems of sucker rod downhole pumps possibly related to formation solids operated by OMV Austria GmbH in Lower Austria and to introduce measures to improve the runtimes of the pumps. A close look was taken at the geological aspects of the fields in which sucker rod pumps (SRP) are used to extract crude oil from the ground. Subsequently, the nature and causes of sand production, as well as measures available in the industry against sand problems were reviewed. In addition, an overview of OMV’S SRP specifications is given to understand SRP failures and the materials that are used to manufacture the different pump parts. Moreover, different SRP models and components, which have been used over the years at the production site in Gaenserndorf, were described and the best performing pumps were compared to each other. Workovers and well interventions were tracked and show that 43% of all well interventions are due to failures of the downhole pump itself, followed by tubing leaks, sand accumulation and broken rods. As a consequence of this finding, a SRP failure database of the company, which was initiated in 2011, was analysed. However, the data quality is insufficient because the failure form is complicated and allows biased declaration of the failures, which prevents a meaningful analysis of the collected data. Thus, the data set was processed manually and as a result of this finding a new failure form, including new failure categories, is suggested. The analysis of the data shows that the 25-150 RHAC 21-4 insert pumps have the shortest average runtimes of 337 days and the highest failure frequency of 0.25. Scatter plots were used to find out about trends on the runtime and lead to the conclusion that this pump type has the poorest performance due to its application in deep wells with low liquid levels. When the failures were investigated further, it was revealed that 35% of pump stops arise from a failure of the standing valve, 28% from failures of the barrel and 23% from failures of the traveling valve. The valve rod guide failed in 12% of the cases and the plunger in 2%. With the knowledge of the failure reasons possible solutions for SRP were described focusing on feasibility and cost efficiency. In addition, a runtime analysis of a non API plunger, which is referred as Farr plunger, was performed. After three years of utilization of this plunger, conclusions about its effectiveness can be made. It was found out that the Farr plunger is not an optimal choice when it comes to sand production. Comparison of runtimes of conventional plungers systems, previously installed in the same wells, show that the runtime of the Farr plunger systems is 165 days, in contrast to the average runtime of 284 days for pumps equipped with conventional plungers.