WELL PRODUCTION PERFORMANCE ANALYSIS FOR UNCONVENTIONAL SHALE GAS RESERVOIRS; A CONVENTIONAL APPROACH FLORIN HATEGAN Devon Canada Corporation
BACKGROUND Shale Gas HZ Drilling, Multi-Stage Hydraulic Fracturing: Today is the norm throughout the industry Very High Drilling & Completion costs Performance Evaluation complex and controversial SUCCESS IS RESERVOIR SPECIFIC FIELD ANALOGIES CAN BE DANGEREOUS ABSTRACT CONCEPTS SUCH AS S.R.V., OR F.C.A. WRONGLY USED AS DEFINING PARAMETERS IN-SITU RESERVOIR PARAMETERS SUCH AS PORE PRESSURE AND PERMEABILITY ARE TO OFTEN OVERLOOKED, OR IGNORED
PRESENTATION OVERVIEW Introduction Stimulated Reservoir Volume (SRV) Linear Flow Spreadsheets Analytical Model Construction Pseudo Steady State Equation Solution Reservoir Pressure Permeability or Flow Capacity Completion Skin Drainage Area and Shape Field Case Examples NORMALIZED SHALE GAS PRODUCTION PLOT In-Situ Testing for D&C Optimization Field Case Example Conclusions
INTRODUCTION PERFORMANCE EVALUATION SHALE GAS PRODUCTION CAN NOT BE ANALYZED BY CONVENTIONAL METHODS (e.g. DARCY LAW) PRODUCTION PERFORMANCE IS MAINLY A FUNCTION OF STIMULATED RESERVOIR VOLUME (SRV) USE OF LINEAR FLOW SPREADSHEETS CHALLENGE SHALE GAS PERFORMANCE CAN BE MODELLED ANALYTICALLY USING PSEUDO STEADY-STATE SOLUTION ONLY 4 (Four) KEY FORECST PARAMETERS: Reservoir Pressure Matrix Permeability (In-Situ) Completion Skin Drainage Area & Shape per Stage (correlated to Pi, k & s ) ANALYTICAL MODEL = Superposition of Solutions for Pseudo Steady-State Equation Applied to Individual Frac Stages
Stimulated Reservoir Volume (SRV) The most talked about concept introduced after successful HZ-MSF developments in the Barnett Shale and elsewhere Thousands of publications, articles and presentations on this topic SRV may be over-rated or misunderstood
Stimulated Reservoir Volume (SRV) Microseismic Mapping
Stimulated Reservoir Volume (SRV) Integration of Microseismic into Reservoir Simulator
Stimulated Reservoir Volume (SRV) Integration of Microseismic into Reservoir Simulator
Stimulated Reservoir Volume (SRV) Integration of Microseismic into Reservoir Simulator SRV gridding and K srv distribution
Stimulated Reservoir Volume (SRV) IN-SITU SHALE GAS MATRIX CONFIGURATION: THIN SECTION MATRIX & NAT. FRACTURES
Stimulated Reservoir Volume (SRV) IN-SITU SHALE GAS MATRIX CONFIGURATION: THIN SECTION MATRIX, NO NAT. FRACTURES
Stimulated Reservoir Volume (SRV) MATRIX & NAT. FRACTURES MATRIX, NO NAT. FRACTURES
Stimulated Reservoir Volume (SRV) EVIDENCE OF SHALE MATRIX WITH NO IN-SITU NAT. FRACTURES:
Linear Flow Spreadsheets
Rate (Mcf/D) dm(p)/q q/dm(p) dm(p)/q Pressure Rate dm(p)/q Linear Flow Spreadsheets 6.0E+06 5.0E+06 4.0E+06 3.0E+06 2.0E+06 WELL NAME HERE 1000 900 800 700 600 500 400 300 10000 1000 100 WELL NAME HERE 4.0E+06 3.0E+06 2.0E+06 1.0E+06 WELL NAME HERE 1.0E+06 0.0E+00 0 10 20 30 40 50 Sqrt t 200 100 0 10 1 10 100 1,000 10,000 Time Daily Production AOF EHS Test 0.0E+00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Cum (Bcf) Actual Fitted tehs WELL NAME HERE WELL NAME HERE WELL NAME HERE 10,000 1.0E-04 1,000 1.0E-05 3.0E+06 1.0E-06 2.0E+06 100 1.0E-07 10 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Cum (Bcf) Actual Fitted tehs 1.0E-08 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Cum (Bcf) Actual tehs 1.0E+06 1.0E+04 0 10 20 30 40 50 60 Sqrt t
Linear Flow Spreadsheets Input Data Results
ANALYTICAL MODEL CONSTRUCTION Pseudo Steady-State Equation General Using Gas Pseudo-Pressure
ANALYTICAL MODEL CONSTRUCTION Reservoir Pressure Initial Reservoir Pressure (Pi) Pre-Frac Tests Conventional FBU Tests As soon as possible after completion Watch balance of flow time and buildup time Requires long shut-ins (1 month +)
ANALYTICAL MODEL CONSTRUCTION Reservoir Pressure: 200 h Flow & 1 Mo BU p* = 31330 kpaa
ANALYTICAL MODEL CONSTRUCTION In-Situ Matrix Permeability & Total Completion Skin Most difficult to obtain Require recalibration with early time production data First step: k m from initial FBU: Field example: SHALE 1 HZ-MSF 9 Stages Initial FBU Analysis: (kh) t = 1.9 mdm, s = - 4.41 Divide (kh) t by net pay and nr. of frac stages: k m = 0.0031 md
ANALYTICAL MODEL CONSTRUCTION Drainage Area and Shape Observed Strong Correlation between k and A
ANALYTICAL MODEL CONSTRUCTION Drainage Area and Shape (Per Frac Stage) APPARENT EFFECTIVE DRAINAGE AREA Extrapolate to cover shale gas permeability range Drainage Shape: requires more work (L:W Ratio = 3:1)
ANALYTICAL MODEL CONSTRUCTION ANALYTICAL MODEL = Superposition of Solutions for Pseudo Steady-State Equation Applied to Individual Frac Stages
Gas (10 3 m 3 /d) ANALYTICAL MODEL Pressure (kpa) Rate (10 3 m 3 /d) Pressure (kpa) CONSTRUCTION RECALIBRATE MATRIX PERM & SKIN k m = 0.0015 md s = - 5.2 Production History 160 140 Legend Tubing Pressure Bottom Hole Pressure Actual Gas Data 28000 24000 120 20000 100 16000 HZ-MSF Model 80 12000 180 History Match 60 8000 160 140 Legend 30000 25000 40 20 4000 0 120 100 80 Flow Press Gas Rate Syn Res Press, P is calculated Syn Flow Press 20000 15000 0 10 20 30 40 50 60 70 80 90 Time, days 60 10000 40 20 5000 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 0 Time (d)
ANALYTICAL MODEL CONSTRUCTION ANALYTICAL MODEL (UPDATE):
ANALYTICAL MODEL CONSTRUCTION ANALYTICAL MODEL & PRODUCTION UPDATE
ANALYTICAL MODEL ANALYTICAL MODELS & PRODUCTION UPDATES:
ANALYTICAL MODEL BARNETT SHALE Example
SHALE GAS SHALE GAS MODELS USING PSEUDO STEADY STATE SOLUTION
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : DIVIDE TOTAL WELL PRODUCTION RATE BY: Nr. Frac Stages (n) Initial Pressure (Pi) Flow Capacity (kh)
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)
NORMALIZED SHALE GAS PRODUCTION SHALE GAS NORMALIZED PRODUCTION PLOT : Nr. Frac Stages (n), Initial Pressure (Pi) and Flow Capacity (kh)
IN-SITU SHALE GAS TESTING Several Testing Techniques Are Used To Test Shale Gas Formations Prior Completion: Diagnostic Fracture Injection Test (DFIT) Wireline Formation Tests (RFT, MDT, CHDT ) Perforation Inflow Diagnostic (PID)
IN-SITU SHALE GAS TESTING SHALE GAS PID TESTING: FIELD EXAMPLE (SHALE 1 Vertical Well)
IN-SITU SHALE GAS TESTING SHALE GAS PID TESTING: FIELD EXAMPLE (SHALE 1 Vertical Well)
IN-SITU SHALE GAS TESTING SHALE GAS PID TESTING: D&C OPTIMIZATION
CONCLUSIONS 1. Shale gas HZ-MSF well performance can be derived using simple, conventional analytical models. 2. In-situ shale gas reservoir properties (Pi & k) and shale fabric (presence of natural fractures) will control the production performance of HZ-MSF wells 3. Misinterpretations of SRV will account for significant overestimations of long-term cumulative production 4. HZ-MSF has a cumulative effect on well production by adding in-situ FLOW CAPACITY and not by CREATING better reservoir on a large areal extent 5. NORMALIZED PRODUCTION PER FRAC STAGE IS ONE OF THE BEST TOOLS FOR D&C OPTIMIZATION 6. Pi & k for shale gas can be obtained using PID testing.
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