Oilwell Deliverability Monitoring: A Case History
- T.S. Thrasher (Phillips Petroleum Co.) | E.J. Fetkovich (Phillips Petroleum Co.) | S.L. Scott (Phillips Petroleum Co.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Engineering
- Publication Date
- November 1995
- Document Type
- Journal Paper
- 293 - 300
- 1995. Society of Petroleum Engineers
- 1 in the last 30 days
- 484 since 2007
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This paper presents a case history study that demonstrates a method to monitor wellhead deliverability performance for flowing oil wells in a manner similar to gas wells. Separator test data measured for production allocation are used along with the material balance relationship and multiphase flow analysis to develop a wellhead backpressure curve for flowing oil wells. An equivalent wellhead static pressure for flowing oil wells is described and shown to be a function of reservoir depletion and multiphase flow rate. Determination of the equivalent wellhead static pressure extends our understanding of wellhead backpressure analysis for both flowing oil and flowing gas wells.
A case history example is developed which demonstrates the application of the methods described in the paper using the separator test data from the Point Arguello Field wells, operated by Chevron for the Chevron-Phillips-Union Pacific Resources group, offshore California. The resulting wellhead backpressure curves clearly define individual well deliverability and were proven to be valuable diagnostic tools to monitor well performance and quantify production potential. The procedures developed in this paper are shown to be directly equivalent to procedures applied to conventional gas well wellhead backpressure analysis that are commonly used in the industry to monitor gas well performance. Monitoring flowing oil well performance with the methods described in this paper, operators can address the challenge of maintaining well productivity and field production plateau.
The concept of equivalency between gas and oil well bottom hole backpressure relationships was introduced and described in the classic paper by Fetkovich. This work demonstrated that oil wells behave very similarly to gas wells and should be tested and analyzed using the same basic flow equations. Fetkovich discovered from the analysis of over 40 oil well backpressure tests that oil well bottom hole backpressure curves followed the same general form of the equation used to express the rate-pressure relationship for gas well bottom hole backpressure curves:
This paper extends the work of Fetkovich and demonstrates with field data that the wellhead performance of flowing oil wells can be analyzed using separator test rate-pressure data. The same general form of the equation used to express the wellhead rate-pressure relationship for flowing gas well backpressure curves can be used for flowing oil well backpressure curves:
A study was conducted for the Point Arguello Field that focused on identifying any 'unrealized' bottom hole and wellhead productivity potential from these high volume flowing oil wells. Based upon the analysis methods discussed in this paper, bottom hole and wellhead backpressure curves were developed for each well in the field. Backpressure analysis identified several tubing restricted wells and quantified additional deliverability.
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