01 introduction well testing

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Well Test Analysis Instructors: Bui Tu An (PVU) Huynh Thanh Tung (Schlumberger) Nguyen Tuan Duong (VSP) TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course information Credit: 02 (36 hours) Grading • In-class evaluation: 25% • Midterm: 25% • Final Examination: 50% Text materials Lee, W.J.: Pressure Transient Testing, SPE (2003) Spivey John P , Lee W.John: Applied Well Test Interpretation, SPE (2013) Software Tools Microsoft Excel Ecrin - KAPPA TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course Description  Analysis of well performance under varied reservoir conditions including evaluation of unsteady, pseudo-steady and steady state flow;  Well testing methods used to determine well and reservoir parameters; applications to conventional unconventional wells producing gas and/or liquids; and  The fundamentals for preparing and operating well test equipment to monitor, measure, and gather samples for evaluating well performance TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course Learning Outcomes Describe the terminology and the commonly-applied methods for quantifying and predicting well performance, specifically skin, horizontal and vertical permeability, and fracture area and permeability; Develop the ability to use diagnostic plots to identify flow regimes and well drainage patterns; Apply pressure transient well test analysis to the determination of well and reservoir properties, i.e., skin, permeability, distance to barriers, Apply rate transient well test analysis to the determination of well and reservoir properties, i.e., skin, permeability, reservoir volume TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course content Introduction of well testing (2x45 minutes) Review of fluid (oil & gas) properties (1.5x45minutes)  Solution Gas-Oil Ratio, Viscosity, Density, Formation Volume Factor, Specific Gravity, Gas Compressibility … Fundamentals of Fluid Flow in Porous Media (2.5x45minutes)  Material balance, equation of state and Darcy’s Law  Development of the diffusivity equation: Liquid and gas systems TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course content Solutions/models for Well Test Analysis (2x45 minutes)  Dimensionless variables  Steady-state, pseudosteady-state, and transient flow in radial and other geometries  Adding near wellbore and wellbore phenomena Well Test Analysis (4x45 minutes)  Analysis of pressure drawdown/buildup data for Slightly Compressible Fluids  Analysis of pressure Compressible Fluids drawdown/buildup data for  Analysis by use of Type Curves TALENTS FOR DEVELOPMENT @MSc Bui Tu An Course content Use software for the analysis of well test data Huynh Thanh Tung (Schlumberger) (12x45 minutes) Preparing and operating well test equipment Nguyen Tuan Duong (VSP) (12x45 minutes) TALENTS FOR DEVELOPMENT @MSc Bui Tu An What is a Well Test?  The technique and method for the evaluation of well conditions and reservoir characteristics  Investigates a much larger volume of the reservoir than cores or logs  Provides estimate of permeability under in-situ conditions  Provides estimates of near-wellbore condition  Provides estimates of distances to boundaries  It involves producing a well at a constant rate or series of rates, some of which may be zero (well closed in), while simultaneously taking a continuous recording of the changing pressure in the wellbore (at the same well or another well) using some form of pressure recording device TALENTS FOR DEVELOPMENT @MSc Bui Tu An How is a Well Test Conducted? A well test is conducted by: • Changing production rate at a well • Measuring resulting pressure response at the same well or another well TALENTS FOR DEVELOPMENT @MSc Bui Tu An Well Test Applications  Exploration  Is this zone economic?  How large is this reservoir?  Reservoir engineering  What is the average reservoir pressure?  How I describe this reservoir in order to – – – estimate reserves? forecast future performance? optimize production?  Production engineering  Is this well damaged?  How effective was this stimulation treatment?  Why is this well not performing as well as expected? TALENTS FOR DEVELOPMENT @MSc Bui Tu An 10 Types of Well Tests q Single-Well TALENTS FOR DEVELOPMENT Multi-Well @MSc Bui Tu An 13 Single well tests  Drawdown test – Produce a well at constant rate (or multirate) and measure the pressure response TALENTS FOR DEVELOPMENT @MSc Bui Tu An 14 Single well tests  Buildup test – Shut in a well that has been producing and measure the pressure response TALENTS FOR DEVELOPMENT @MSc Bui Tu An 15 Single well tests  Injection test – Inject fluid into a well at constant rate and measure the pressure response  Injection-falloff test – Shut in an injection well and measure the pressure response TALENTS FOR DEVELOPMENT @MSc Bui Tu An 16 Multi-well tests  Interference test – Produce one well at constant rate and measure the pressure response at one or more offset wells  Pulse test – Alternately produce and shut in one well and measure the pressure response at one or more offset wells TALENTS FOR DEVELOPMENT @MSc Bui Tu An 17 Well Test Methods The primary ways to test a well are covered in the following sections Open hole and cased hole, no completion  Conventional deliverability tests, involving extensive surface and downhole equipment, are designed to simulate the production characteristics of new wells TALENTS FOR DEVELOPMENT @MSc Bui Tu An 18 Well Test Methods Figure shows a typical surface offshore layout for an exploration well test and a sketch of the drillstem test (DST) string of downhole testing tools TALENTS FOR DEVELOPMENT @MSc Bui Tu An 19 Well Test Methods Wireline formation tests (WFT) Wireline tests (Repeat Formation Tester - RFT or Modular Formation Dynamics - MFD) are performed mostly in open hole using a cable-operated formation tester and sampling tool anchored at depth while reservoir communication is established through one or more pressure and sampling probes Figure shows typical configurations for testing and sampling with the MDT TALENTS FOR DEVELOPMENT @MSc Bui Tu An 20 Well Test Methods Production or injection test with completion string in place  Production and injection well tests, performed using production logging tools, are conducted to obtain pressure and optional flow measurements Figure shows a sketch of a basic version of the PS Platform* new-gener-ation production services platform, equipped with a gas holdup sensor TALENTS FOR DEVELOPMENT @MSc Bui Tu An 21 Well Test Methods Mini-DST  The Mini-DST tool uses the conventional Wireline Formation Tester (WFT) configured with a dual-packer module and downhole pump  The operation of mini-DST tool requires much less time than the classic DST, and multiple zone tests can be conducted to assess individual zone deliverability  On the other hand, the mini-DST has definitely increased reliability and the success rate of pressure transient tests TALENTS FOR DEVELOPMENT @MSc Bui Tu An 22 Well Testing - Data Acquisition  Downhole Recorders  Record pressure and temperature  Components − Pressure Gauge − Power Source − Memory unit  to recorders used  Surface pressure readout (Wireline link) TALENTS FOR DEVELOPMENT @MSc Bui Tu An 23 Well Test Data Analysis  Diffusivity Equation  Model Recognition  Interpretation  Straight-Line  Type-Curve  Simulation and History Matching TALENTS FOR DEVELOPMENT @MSc Bui Tu An 24 To sum up : Well Test  A properly designed, executed, and analyzed well test can provide information:  formation permeability  reservoir initial or average pressure  sand-face condition (well damage or stimulation)  volume of drainage area  boundary and discontinuities  reservoir heterogeneity  distance or extension of the fracture induced  validation of geological model  Further, it is important to determine the ability of a formation to produce reservoir fluids and underlying reason for a well's productivity TALENTS FOR DEVELOPMENT @MSc Bui Tu An 25 To sum up : Well Test  Well Test data when combined with hydrocarbon production data, and laboratory data on fluid and rock properties:  afford the means to estimate the original hydrocarbon inplace, and  the recovery that may be expected from the reservoir under various modes of exploitation  In addition, well test data and IPR well performance equations, combined with production data, help to design, analyze, and optimize total well production system or production optimization TALENTS FOR DEVELOPMENT @MSc Bui Tu An 26 TALENTS FOR DEVELOPMENT @MSc Bui Tu An 27 ... pressure in the wellbore (at the same well or another well) using some form of pressure recording device TALENTS FOR DEVELOPMENT @MSc Bui Tu An How is a Well Test Conducted? A well test is conducted... DEVELOPMENT @MSc Bui Tu An 12 Types of Well Tests q Single -Well TALENTS FOR DEVELOPMENT Multi -Well @MSc Bui Tu An 13 Single well tests  Drawdown test – Produce a well at constant rate (or multirate)...  Analysis of well performance under varied reservoir conditions including evaluation of unsteady, pseudo-steady and steady state flow;  Well testing methods used to determine well and reservoir