- To develop a methodology for making low compressive strength cores that will represent the average reservoir producing with the CHOPS process in Alaska.
- To experimentally model wormhole propagation during CHOPS in the laboratory as a function of core permeability and porosity, compressive strength, oil/water viscosity contrast, confining pressure and injection rate. Modeling the wormhole propagation will enable us be able to develop approximate inflow performance relationship (IPR) for wells producing using this completion methodology.
- To build a multiphase flow loop that will be used to measure pressure drop during multiphase flow of gas, water, heavy oil and sand.
- To use the results from the above flow loop to develop correlations that relate pressure drop in pipe to gas, water, heavy oil and sand flow rates.
Impact to Alaska
Alaska’s North Slope is a world class petroleum resource. With a steep decline in light oil production the focus is now on the vast resource of untapped heavy oil. One of the prospective techniques used to exploit this resource is the CHOPS process. It involves deliberate production of sand from the reservoir along with the hydrocarbons resulting in the formation of wormholes (channels filled with sand suspended in foamy oil) enhancing the reservoir permeability near wellbore. This research will that help characterize wormhole development (therefore IPR) and the pressure drop in the wellbore (lift performance) necessary for optimal field development and well completion strategies. This will in turn lead to increased production. This outcome will have direct financial impacts on the State of Alaska.
We will conduct (1) core flooding experiments in order to investigate wormhole development in cores and (2) flow experiments in order to decipher flow patterns and measure pressure drop during the multiphase flow of gas, water, heavy oil and sand.
- Wormhole characterization—Sand blends have been developed to prepare synthetic cores (Figure 1). Dependence of synthetic core properties on the water to cementing material ratio is shown in Figure 2. The range of experimental parameters is shown in Table 1. These ranges can be modified based on experimental results. To simulate wormhole propagation during the CHOPS process, water will be injected using a syringe pump into floating piston accumulator to push the oil ahead of piston to oil saturated core in core holder. The differential pressure across the core will be monitored throughout the flooding process and the cores will be scanned using computerized tomography (CT) before and after flooding to identify wormhole propagation. These indicators will help us characterize the nature and growth of wormholes. Samples of produced water, oil and solids will be collected and measured. This apparatus can be sued in the future to test the efficiency of various EOR (Enhanced Oil Recovery) processes. This setup will be ready for use by the end of May 2015.
- Heavy Oil Production with Sand Multiphase flow loop—A multiphase flow loop capable of measuring and recording solid and fluid rates/pressures will be built at the University of Alaska, Fairbanks. Heavy oils of viscosities ranging from 200 to 1000 cp will be flowed through this setup and the results will be used to build flow pattern maps. Pressure drop correlations will be developed for each of these flow patterns. Figure 3 is a representation of the experimental setup. Figure 4 and 5 show the effect of sand on elongated bubbly flow morphology.
- Understand how the various factors investigated affect wormhole propagation.
- Use the above understanding to develop approximate IPR models for wells completed with the CHOPS process.
- Develop multiphase flow pattern maps specifically for heavy oils.
- Develop lift performance correlations for sand-laden heavy oil under a variety of flow conditions.
- Study the fundamental concepts affecting the transport of solids in fluid mixtures.
- To be able to support the multiphase flow testing needs of companies that operate in the State of Alaska.
- Move the multiphase flow loop to a bigger facility that will accommodate testing of larger pipe diameters—this is because it is anticipated that the Trans-Alaska pipeline will be transporting heavier crudes (albeit cut with lighter crude) in the future. It is our hope that this laboratory will be able to meet the testing needs that will definitely arise as a result of this shift.
- Narayan, A., Awoleke, O.O., Ahmadi, M. & Liu, J. 2016. An Investigation into the Cold heavy Oil Production with Sand Process Using Synthetic Cores and Designed Experiments. SPE Western Regional Meeting, Anchorage, Alaska, 23-26 May. SPE-180373
- Hulsurkar, P., Awoleke, O.O. & Ahmadi, M.. 2017. Experimental Study of the Multiphase Flow of Sand, Viscous Oil and Gas in a Horizontal Pipe. SPE Annual Technical Conference and Exhibition, to be held in San Antonio, Texas, 9-11 October. SPE-187212-MS
Contact: Dr. Dare Awoleke