Multilateral Well Simulation (MLATSIM) software predicts well performance and enables “what-if analysis”—serving to potentially improve well performance, mitigate the likelihood of cease flow in the laterals, and increase production significantly at minimal cost to the operator. Furthermore, extending the typical 2-3 year “production peak” for a multilateral well reduces the need to drill new wells and expend capital to maintain production.
The MLATSIM Model predicts the flow of oil, gas and water from upstream production facilities, namely multilateral/horizontal oil and gas wells. The model uses the core Black Oil Model and a convergence superstructure to synthesize information from the reservoir inflow, drainhole, transition to vertical well flow, and total system performance. Because the model utilizes the core Black Oil Model, it contains the same functionality and all core Black Oil Model features and flexibility. Some of these features include the ability to:
- Model artificial lift (including submersible pumps and gas lift)
- Simulate integrated systems of well+surface flowline (i.e. reservoir-to-terminus simulation)
- Predict unstable flow regimes in the laterals, enabling the evaluation of operational and design measures directed at increasing production and avoiding cease flow.
Overview of Recent Project
For Saudi Aramco, EnSys Yocum evaluated a well in the Ghawar oil field with two close-interval horizontal laterals. After conferring with Aramco engineers and analyzing configurational and fluid properties data, EnSys Yocum ran a base case MLATSIM simulation to reflect current production. The above diagram describes the system configuration with the two laterals flowing into the vertical oil well.
API degrees gravity: 32.5˚
Gas-oil-ratio: 500 scf/bbl
Our base case output for the multi-lateral well indicated a close match (within 5%) against recent wellhead test separator data for the well.
Once the current production system had been accurately modeled, EnSys Yocum reviewed the results with the Aramco engineers and MLATSIM was applied to undertake “what-if analysis”—namely, to assess the impact of making changes to this system to increase oil production.
With Aramco’s guidance in establishing the premises, EnSys Yocum conducted a series of simulations to assess different ways of achieving well performance improvement (the applicability of these measures is described in a recent JPT article referenced below):
1. Reduce the wellhead pressure
2. Install a pump in the vertical well
3. Take measures to reduce the water fraction
4. Start gas injection
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Journal of Petroleum Technology, “Artificial Lift Experts Warn of Long-Term Production issues in Horizontal Wells“, October 2015, page 50.