Case Study: Modeling of a Large-Scale Tight-Gas Gathering System
- Brett K. Stevenson (ExxonMobil Corp.) | Casey D. O'Shea (Fekete Associates Inc.)
- Document ID
- Society of Petroleum Engineers
- SPE Projects, Facilities & Construction
- Publication Date
- September 2006
- Document Type
- Journal Paper
- 1 - 5
- 2006. Society of Petroleum Engineers
- 4.1.5 Processing Equipment, 1.6 Drilling Operations, 4.1.6 Compressors, Engines and Turbines, 5.8.1 Tight Gas, 4.1.2 Separation and Treating, 5.1.7 Seismic Processing and Interpretation, 4.1.9 Heavy Oil Upgrading, 5.7 Reserves Evaluation, 5.6.9 Production Forecasting, 4.2 Pipelines, Flowlines and Risers, 4.3.4 Scale, 3.1.5 Plunger lift
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This case study outlines the techniques used to model the Williams Production Rocky Mountain Co. Grand Valley gas-gathering system in the Piceance basin. The results of the modeling exemplify how a nodal-analysis model can become an invaluable tool for optimizing the performance of gas-gathering systems and planning future system expansion.
Field production in the Grand Valley gathering system varies minute by minute, creating a dynamic system that is difficult to model with standard practice. By use of an innovative statistical method to handle the scale and complexity of the system, the model has simulated the true flowing conditions of the system over the last 5 years consistently and accurately. The model has been used to successfully locate and quantify substantial static and frictional pressure losses. As the field develops, proposed drilling programs are added to forecast the impact of the new wells on the system. Various pipeline and compressor-expansion scenarios are tested to determine the most effective locations and cost-viable options.
Recommendations from the model have been implemented successfully and have played an integral role in the expansion of the gathering system. The model has been used to identify exact locations of pressure losses, help plan for incremental drilling volumes, and quantify the additional costs incurred from third-party gas entering the system.
This paper explains how a model can assist in the successful development of a large-scale, high-volume, and dynamic gas-gathering system. Details of the modeling procedure and highlights of the innovations implemented to meet the challenging operating conditions and aggressive development of this field are presented.
The Piceance basin in western Colorado is one of the most rapidly developing areas of unconventional gas production in the United States. The gas is produced from the Mesaverde group, which consists of sands interbedded with shale. The main target formation is the tight, discontinuous, lenticular sands of the Williams Fork formation. The net pay of the formation is thick—generally hundreds of feet deep—but the low permeability of the formation substantially limits flow potential. There are also several wells producing from the Wasatch and Rulison formations. The production from these shallower zones accounts for approximately 1% of the total field production.
Development of the fields has been historically slow because of marginally economic flow rates. Recent high gas prices and increased consumer demand have accelerated basin development in the past few years, and infill and step-out drilling have increased the assigned reserves of these fields significantly.
While the reserves of the basin are extensive, the drainage area of a single well is quite small, limiting the recoverable reserves on a per-well basis to approximately 1.0 to 1.2 Bcf. A large number of wells is required to deplete the resource within an economic time frame. Throughout the history of the fields, the interwell spacing has been successively decreased from 80 to 20 acres. At the current spacing of 20 acres, the production history has shown minimal interference between the wells. A pilot project currently is being conducted to determine the feasibility of decreasing the interwell spacing to 10 acres.
Over the last 5 years, in the midst of rapid expansion, Williams has used a nodal-analysis model to plan the development of their gas-gathering system successfully. From 2000 to 2005, the model was updated on a yearly basis. Because of the continuous system expansions and upgrades, Williams is now updating the model on a monthly basis.
|File Size||957 KB||Number of Pages||5|
Crane Co. 1969. Flow of Fluids Through Valves, Fittings and Pipe. TechnicalPaper 410. 1-8. Houston.
McNeil, R.G. and Lillico, D.R. 2005. Gas Gathering System Modeling—ThePipeline Pressure Loss Match. Paper presented at the Canadian Intl. PetroleumConference, Calgary, June.