Hollow Sucker Rod Criteria and Applications
Research output: Research › Master's Thesis
The decline in world oil prices over the last year’s forces oil and gas companies to produce oil and gas more efficient than ever before. One of the most efficient artificial lift (AL) methods used nowadays is the progressing cavity pump (PCP). Progressing cavity pumps are used in wells where other types of AL are not suitable or inefficient e.g. dewater gas wells or production of heavy oil, but this method also has several limitations in regards of the used rod string to drive the PCP, the setting depth and downhole temperature. This thesis describes the major requirements and limitations on a PCP system and on a rod string. Furthermore, the initial development of hollow sucker rods is described in detail. This new technology increases the torque capacity of the rod string and allows the injection or production of fluids within the hollow rod. Hollow sucker rods could be used for different recovery methods like PCP or sucker rod pumping (SRP) applications. Therefore, a literature review was done to summarize the different application possibilities. Heavy oil production with steam assisted gravity drainage is only one option out of several which are presented within this thesis. These rods also have the potential to increase production and reduce downtime/replacement costs for sucker rod pumping units by injection of chemical inhibitors or hot water directly to the area where the treatment is necessary. To assess the potential market for these rods, a market as well as competitor analysis was done. The whole artificial lift market is worth USD 7.62 Billion to USD 10.4 Billion in 2016, depending on the resources, approximately 7% out of this value belongs to the PCP market. Rod string competitor analysis shows, that the major suppliers further developed the API sucker rods with novel threads and couplings which also increased the torsional capacities. For the development of a novel hollow rod string, the last chapter of this thesis summarizes the load ranges which hollow rods should sustain as well as some suggestions for further novel developments in this area.