Well Test Module 1

Introduction to well testing
Origins of Oil and Gas
Well Casings
Purpose of Well Tests
Well Test Planning
Sub-Sea Equipment
Surface Equipment
Auxiliary Equipment
Well Preparation
Conducting the Well Test
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Almost all of the world's oil and gas produced today comes from accumulations in the pore spaces of reservoir rocks - usually sandstone, limestones or dolomites. The amount of oil and gas contained in a unit volume of reservoir rock is determined by its porosity and the hydrocarbon saturation. In addition, the total volume of the hydrocarbon reservoir is required in order to estimate the total reserves in place and to determine if the accumulation is commercial. Knowledge of the payzone thickness and the areal extent of the reservoir are required for determination of its volume. To evaluate the producibility of a reservoir, the permeability or ease at which hydrocarbon fluids can flow through the pores in the reservoir, must be determined.
Thus, the main petrophysical parameters required to evaluate a reservoir are its porosity (f), hydrocarbon saturation (S), permeability (k) and thickness; these parameters can be estimated from well logging techniques. In addition, the determination of reservoir rock characteristics (lithology), reservoir geometry, formation pressure and temperature, play an important role in the evaluation, completion and production of a reservoir.

Well test hook-up layout

Section	Title	Page Number
2	ORIGINS OF OIL AND GAS	9
2.1	INTRODUCTION	9
2.2	ROCK TYPES	10
2.2.1	Igneous Rocks	10
2.2.2	Sedimentary Rocks	10
2.2.3	Metamorphic Rocks	10
2.2.4	Porosity and Permeability	12
2.3	THE ORIGIN AND ACCUMULATION OF PETROLEUM	14
2.3.1	Geological Traps	14
2.3.2	Anticlines	14
2.3.3	Fault Trap	14
2.3.4	Unconformities	16
2.3.5	Salt Plug Trap	16
2.4	COMMERCIAL OILFIELDS	16
2.5	RESERVOIR DRIVE MECHANISMS	17
2.5.1	Internal Drive	17
2.5.2	External Drive	18

Section	Title	Page Number
3	WELL CASINGS	25
3.1	CASING AND CEMENT	25
3.2	BASIC CASING STRING	28
3.3	CEMENTING EQUIPMENT AND TECHNIQUES	32
3.3.1	Casing Accessories	32
3.4	CEMENTATION	36

Section	Title	Page Number
4	PURPOSE OF WELL TESTS	43
4.1	INTRODUCTION	43
4.2	OBJECTIVES IN WELL TESTING	46

Section	Title	Page Number
5	WELL TEST PLANNING	47
5.1	INTRODUCTION	47
5.2	TEST OBJECTIVES	47
5.3	TEST DESIGN	48
5.3.1.	Types of Well Tests	48
5.4	RIG TYPES	48
5.4.1	Land Rigs	48
5.4.2	Jack-Up Rigs	48
5.4.3	Semi-Submersible rigs	49
5.4.4	Drill Ships	49
5.5	SUB-SEA EQUIPMENT	52
5.6	SURFACE EQUIPMENT	55

Section	Title	Page Number
6	SUB-SEA TEST EQUIPMENT	59
6.1	SUB-SEA SAFETY VALVE FOR JACK UPS	59
6.1.1	Description	59
6.1.2	Design	59
6.2	SUB SEA TEST TREE FOR FLOATERS	61
6.2.1	Description	61
6.2.2	Design	61
6.3	SUB SEA RETAINER VALVE	63
6.3.1	Description	63
6.3.2	Design	63
6.4	SUB SEA LUBRICATOR VALVE	63
6.4.1	Description	63
6.4.2	Design	63
6.5	PRESSURE AND FUNCTION TESTING OF SUB-SEA EQUIPMENT	64

Section	Title	Page Number
7	SURFACE EQUIPMENT	65
7.1.1	Guidelines and Policies	65
7.1.2	Certification	65
7.1.3	Equipment Layout/Operation and Safety	65
7.1.4	Hazardous Zones	65
7.1.5	Regulatory Body Approval	66
7.2	SURFACE TEST TREE	66
7.2.1	Description	66
7.2.2	Design	66
7.3	COFLEXIP HOSES, CHIKSAN PIPES	68
7.3.1	Description	68
7.3.2	Design Requirements	68
7.4	DATA/INJECTION HEADER	69
7.4.1	Description	69
7.4.2	Design Requirements	69
7.5	CHOKE MANIFOLD	70
7.5.1	Description	70
7.5.2	Design Requirements	70
7.6	DOWN HOLE CHOKES	71
7.7	HEAT EXCHANGER	72
7.7.1	Description	72
7.7.2	Design Requirements and Key Specifications	72
7.8	SEPARATOR	74
7.8.1	Description	74
7.8.2	Design Requirements	74
7.9	GAUGE TANK	78
7.9.1	Description	78
7.9.2	Design Requirements	78
7.10	SURGE TANK	79
7.10.1	Description	79
7.10.2	Design Requirements	79
7.11	TRANSFER PUMP	79
7.11.1	Description	79
7.11.2	Design Requirements	79
7.12	DIVERTER MANIFOLD	79
7.12.1	Description	79
7.12.2	Design Requirements	79
7.13	BURNERS AND BOOMS	81
7.13.1	Description	81
7.13.2	Design Requirements	81
7.14	PIPEWORK AND CHIKSANS	83
7.14.1	Description	83
7.14.2	Design Requirements	83
7.15	HOOK UP, PRESSURE TESTING AND CALIBRATION OF SURFACE EQUIPMENT	84
7.15.1	Hook up	84
7.15.2	Pressure Testing	87
7.15.3	Calibration	88

Section	Title	Page Number
8	WELL TEST AUXILIARY EQUIPMENT	89
8.1	AUXILIARY EQUIPMENT	89
8.1.1	Cooling System	89
8.1.2	Air Supply for Burners	89
8.1.3	Emergency Shutdown Systems	89
8.1.4	Chemical Injection Pump	89
8.1.5	Instrument Air	92
8.1.6	Lighting	92
8.1.7	Communication System	92
8.1.8	Standby HP Pump	92
8.2	GENERAL SAFETY POLICIES	92
8.2.1	Drill Pipe and Tubing	93
8.2.2	Crossovers	93
8.2.3	Safety	94
8.3	ADDITIONAL OPERATIONS	95
8.3.1	Wireline Operations	95
8.3.2	Nitrogen Operations	98
8.3.3	Coiled Tubing Operations	98
8.4	ORGANISATION AND RESPONSIBILITIES OF PERSONNEL	102
8.4.1	Rig hierarchy	102
8.4.2	Responsibilities during well testing and well kill	102

Section	Title	Page Number
9	WELL PREPARATION	105
9.1	MINIMUM BOP RAM CONFIGURATION FOR WELL TESTING OPERATIONS	105
9.2	GENERAL PRE-TEST RIG PREPARATION	105
9.2.1	BOP Preparation	105

Section	Title	Page Number
10	CONDUCTING THE WELL TEST	109
10.1	CUSHION EMPLACEMENT	109
10.2	GUIDELINES FOR TEST FLOW PERIODS	110
10.2.1	Opening Up For Initial Flow	110
10.2.2	Well Clean-Up	112
10.2.3	Beaning Up Or Changing From Variable To Fixed Choke	115
10.3	PROCEDURES AND GUIDELINES FOR WELL TEST EQUIPMENT	117
10.3.1	Selection of Separator Operating Pressure	117
10.3.2	Separator Bypassing	118
10.3.3	Heater Usage and Operating Procedures	118
10.3.4	Usage of Surge Tanks and Gauge Tanks in Conjunction with Separators	120
10.4	SURFACE EQUIPMENT MONITORING DURING TESTING	121
10.5	PROCEDURES AND GUIDELINES FOR SHUTTING IN WELLS	121
10.5.1	Surface Shut-In	122
10.5.2	Downhole Shut-In	123
10.6	MEASUREMENTS WHILE TESTING	124
10.6.1	Bottomhole Measurements	124
10.6.2	Surface Measurements	125
10.7	SAMPLING	129
10.7.1	PVT Sampling and Well Conditioning	129
10.7.2	Data Required Prior to Sampling	129
10.7.3	Well Conditioning	129
10.7.4	Bottomhole Sampling	129
10.7.5	Reservoir Fluid Sampling Tools and Equipment	131
10.7.6	Flow-Through Samplers	131
10.7.7	Positive Displacement Samplers	131
10.7.8	Single Phase Samplers	132
10.7.9	Sampler Selection	132
10.7.10	Additional Bottomhole Sampling Equipment Requirements	132
10.7.11	Bubble Point Determination	133
10.7.12	Surface Sampling	137
10.7.13	General Safety Aspects of Sampling	139
10.8	VALIDATION	140
10.8.1	Downhole Gauge Data	140
10.8.2	Surface Flow Data	140
10.8.3	Sampling	140
10.9	DATA ACQUISITION SYSTEMS	141
10.9.1	Surface Sensors	142
10.9.2	Downhole Gauges	143
10.9.3	Strain Gauges	143
10.9.4	Capacitance Gauges	144
10.9.5	Quartz Capacitance Gauges	144
10.9.6	Quartz Crystal Gauges	144
10.9.7	Calibration of Electronic Gauges	144
10.9.8	Mechanical Gauges	145
10.9.9	Surface Readout (SRO)	145

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