The Use of Water Injection for CO 2 Sequestration in Coalbeds

Transcription

1 23 rd International Pittsburgh Coal Conference The Use of Water Injection for CO 2 Sequestration in Coalbeds Miguel Tovar and Shahab D. Mohaghegh, West Virginia University Presented by September 26 th, 26 Miguel Tovar (CDX Gas, LLC)

2 Agenda Objective The Nature s Sequestration Technique Methodology Studied Cases and Results Conclusions

3 Objective Sequester CO 2 in a CBM formation for an extensive time period (thousands of years), filling the coal cleat system with formation water.

4 Natural Equilibrium of a Coal Formation Water CH 4 molecule Coal surface

5 Dewatering a Coal Formation Water CH 4 molecule Coal surface

6 Desorption of Methane and Gas Production Free methane Coal surface

7 Desorption of Methane and Gas Production Free methane Coal surface

8 Abandoned CBM Well Depleted Reservoir Coal surface

9 CO 2 Injection Process CO 2 molecule Coal surface

10 Free CO 2 on the Cleat System and Adsorbed on Coal Matrix Coal surface

11 Water Injection Water Coal surface

12 New Equilibrium in the Coal Formation Water Nature s Sequestration Technique Coal surface

13 Methodology Run Simulations Model Adjustments Analysis of Results Eclipse Defining Scenarios Conclusions, Publications, Redesign Setting Initial Conditions Model Design Search for Reservoir Data Starting Point

14 Defining the Model

15 Model Design The Synthetic Model and Details of the Local Grid Refinement to Represent the Fracture

16 Reservoir Data Representative Data for the Seam Pocahontas 3 in the Appalachian Basin Parameter Minimum Maximum Most Likely Ash Content (fraction) Depth (ft) Fracture Permeability I (md) Fracture Permeability J (md) Fracture Permeability K (md) Fracture Porosity (fraction) Moisture Content (%) Pressure Gradient (psi/ft) Temperature (Fahrenheit deg) Thickness (ft) Time Constant (days) SBSL (ft) Gas Gravity.624 Matrix Porosity (fraction).1 Sw Matrix (%) 1 Sources: W.P Diamond, J.C. LaScola, D.M. Hyman. The US Bureau of Mines IC 967, CBM Proceedings- Alabama 8911; Methane Recovery from Coalbeds, T. Mroz, J. Ryan, Bryer, US. Scott R. Reeves and Anne Oudinot. Topical Report, U.S.-DOE, DE-FC26-NT4924, June, 24

17 Reservoir Data Methane and CO 2 Langmuir Isotherms Measured for the San Juan Basin Coal. (3,4) Absolute Adsorption (Mscf/ft^3) CH4 CO Pressure (psia) Source: Scott Reeves and Anne Oudinot. Topical Report, U.S.-DOE, DE-FC26-NT4924, Jun 24 Scott Reeves, Anne Taillefert and Larry Pekot, Topical Report, U.S.-DOE, DE-FC26-NT4924, Feb 23.

18 Initial Conditions Model and Layers UPPER LAYER FRACTURE LAYER LOWER LAYER Dual Porosity Systems Matrix Cleats Matrix Cleats Matrix Cleats Scenario 1: H2O saturation 9% Water in the Cleats CO2 saturation 8% 1% CH4 saturation 1% 1% 1% 1% 2% % H2O saturation 1% CO2 saturation 8% 9% CH4 saturation 1% 1% 1% 1% 2% % Scenario 2: No Water in the Cleats

19 Production Rates and Pressure Results for Cases with / without Water in Cleats

20 Cumulative Gas Production Results for Cases with / without Water in Cleats

21 CO 2 Production Rate Results as Function of Fracture Height (Cases with water)

22 Cumulative CO 2 Production Results as Function of Fracture Height (Cases with Water)

23 Production Rates Results with Changes in Permeability of Natural Fracture (Cases with Water)

24 Cumulative Production Results with Changes in Permeability of Natural Fracture (Cases with Water)

25 Production Rates Results as Function of Natural Fracture Width (Cases with Water)

26 Cumulative Production Results as Function of Natural Fracture Width (Cases with Water)

27 CO 2 Production Rates Results as Function of Fracture s Nature (Cases with Water)

28 Cumulative CO 2 Production Results as Function of Fracture s Nature (Cases with water)

29 Production Rates Results as Function of Well Geometry (5 ft separation, Cases with Water)

30 Production Rates Results as Function of Well Geometry (1 ft separation, Cases with Water)

31 Cumulative Production Results vs. Well Geometry (Fracture Height = 5 ft, Cases with Water)

32 Cumulative Production Results vs. Well Geometry (Fracture Height = 1 ft, Cases with Water)

33 Conclusions The presence of water in the cleats results in an extensive reduction in the amount of CO 2 seeped from the lower layer into the upper layer for all the cases studied. Results obtained indicate that even in worst case scenarios, CO 2 production rates and CO 2 cumulative production are relatively low, when water fills the cleats. Higher values of permeability and width for natural fractures increases the seepage of CO 2.

34 Conclusions (cont ) While larger is the separation between layers, lower is the seepage of CO 2 observed through the CO 2 production. Combinations of high deep values (or high separation between layers) and low values of permeability contribute to reduce the CO 2 seepage to upper layer. In the same way, combinations of low deep values with higher permeability values of the natural fracture are favorable to increase the seepage to the upper layer.

35 Conclusions (cont ) Flow mechanisms where the well configuration is a multilateral or a single horizontal well have the production capacity to induce the seepage of CO 2 from the lower layer, as results of the large pressure drawdown created in the upper layer even when the separation between layers is the greatest. Water in the cleats contributes to maintain the CO 2 sequestered in coalbeds, for as long as 5 years of simulations by minimizing the seepage of CO 2 toward upper formations.

36 Thanks for your attention!