Introduction

As the last task for students of HYdepartment, before the final internship, the BEI is a long project allowing last year engineer students to work together for six weeks on an industrial project. 

As a result of a mutual interest, our team has joined the SimKarst project initiated in 2012 by Pr. Han Pingchou, PKU, and Bernard Montaron, Schlumberger China. The ultimate objective of the Simkarst project is to design a 3D reservoir simulator that can make realistic multi-phase flow simulations (gas, water, and oil) in large (20 x 20 km) and complex cave networks made of thousands of caves distributed in 3D space and connected according to a given pattern.

This project is our contribution in order to reach the ultimate objective.

 

 

 

 

Industrial context

Our project have its sources at the Karst reservoirs of Traim Basin in Xinjiang Province, in China. The challenge of our industrial partner "Schlumberger" was to improve the oil production of  the karst reservoirs, giving birth to the SimKarst project.
 
    http://califia.us/Tarim/tbasinanddesert.htm                                                                http://en.wikipedia.org/wiki/Tarim_Basin                                                                              
 
 
Karst reservoirs of Tarim Basin in Xinjiang Province of People’s Republic of China have been verified as an area with large quantities of oil and gas.
 
Carbonate formations of Ordovician age buried at more than 6000-meters depth in Tarim basin contain complex cave systems full of oil and water that are being exploited by Chinese national oil companies: Petrochina Tarim Oil Company, and Sinopec North-West Company.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
www.geocaching.com/geocache/GC43T60_karst-quest
 
Below the network of caves,  an aquifer constituted by a porous medium where water goes up by capillarity effect under oil.
 
When oil is produced from a well, water goes up from the aquifer and a large quantity of oil is blocked due to the complex geometry of the caves. Therefore, a multiphase flow simulator is needed to optimize the production.
 
Very few oil reservoirs in the world produce oil from caves. For traditional reservoirs the oil  is contained in the micro-porosity of rocks with typical pore size less than 30 microns. However, in Tarim carbonate oilfields the karsts form complex networks of connected caves, with some caves larger than 300 meters and height exceeding 10 meters.
 
Existing reservoir simulators applied in the oil and gas industry are designed to simulate fluid flow in porous media governed by Darcy's law. These simulators are not appropriate for simulating fluid flow in cave networks where Darcy's law does not apply. The ultimate objective for schlumberger is to design a 3D reservoir simulator that can make realistic multi-phase flow simulations (gas, water, and oil) in large (20 x 20 km) and complex cave networks made of thousands of caves distributed in 3D space and connected according to a given pattern.
 
Navier Stokes model is impracticable because of complexity of the cave geometry for the boundary conditions and massive calculation and data burden.
 
Bernard Montaron proposed to investigate the feasibility of using cellular automata technology for such a simulator. This is one important objective of the so-called SimKARST project at Schlumberger China Petroleum Institute (SCPI).
 
The first part of the project started in October 2012 with two PKU students that developed a prototype cellular automata software to simulate 2D flow of water and oil in a cell with a simple geometry.This Method which is not based on physics laws but several rules, for example, the oil blocks will always move upwards when the water blocks are on top of them. So this method needs to prove its accuracy.
 
 
Therefore, an experiment on a specific geometry was realized in summer 2013 by two Enseeiht students: Nicolas Sobecki and Thibault Moreau, to verify and assist the development of the simulator.
 
 
The simulator is still under development and more cases are needed to verify its accuracy.
 
The aim of this project is to provide simulation results with different geometry using CFD software.
 
 

Objectives of the project

This project is aiming to:

  • Make a research on the different methods and numerical softwares to simulate two phase flow.‚Äč
  • Using VOF method and level set method to simulate the experiment cases and compare Fluent and Jadim results with it.
  • Simulate two phase flow (oil and water) in different geometry:
  • Plot the outlet oil flow rate and the oil recovery ratio versus time and compare the results given by the two softwares and the different geometry‚Äč
  • Compare the CFD simulations with cellular automata simulations in order to validate the cellular automata.
  • Assist the team working on gas injection with geometry and allow them to explore the technique.