Abstract
An accurate estimation of oil and gas reserves is a key to the success of every field development, and this continues throughout the life of the field. There are several methods available for hydrocarbon reserves estimation and these are analogy, volumetric, decline analysis, material balance and reservoir simulation. The accuracy of any of these techniques depend solely on the type, quantity and quality of the geologic, geophysical, engineering, and economic data available plus the assumptions adopted for technical and commercial analysis. Also, the success of the reserve evaluation rely on the integrity, skill and judgment of the experienced professional evaluators. Thus, this chapter is basically dedicated for volumetric method of hydrocarbon reserve estimation which requires a limited amount of data. This chapter gives an understanding of the input parameters required and the factors affecting the volumetric reserves estimation. The step by step approach on how to calculate hydrocarbon reserves, bulk volume from Isopach map, condensate reserve calculations, an understanding of the deterministic and probabilities methods of reserves estimation are presented here with example cases.
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Petroleum Resource Management System Guideline (2011), Society of Petroleum Engineers
Rzasa MJ, Katz DL (2011) Calculation of static pressure gradients in gas wells. Trans., AIME, 160: 100–105
Standing MB (1977) Volumetric and phase behavior of oil field hydrocarbon systems. Society of Petroleum Engineers, Dallas
Standing MB, Katz DL (1942) Density of natural gases. Trans. AIME, 146: 140–149
Petrobjects (2003) Petroleum reserve estimation methods. www.petrobject.com
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Exercises
Exercises
Ex 3.1
-
I.
State the methods available for reserves estimation and explain when each of the is used
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II.
List and explain the factors affecting reserves estimate
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III.
Why is STOIIP determined from material balance method different from volumetric method?
-
IV.
Give reasons while reserves estimation is often high with volumetric method
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V.
The calculation of STOIIP from volumetric method involves several parameters, state these parameters and the sources where they can be obtained
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VI.
What is the practical implication of taking cut-off in petrophysical data?
-
VII.
What is the factor used to covert acre-ft to stb?
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VIII.
What is the implication of net-to-gross ratio in volumetric estimate of STOIIP?
Ex 3.2
The hydrocarbon contents of a reservoir were determined from the data of cumulative bulk volume (CBV) at the indicated depths on the table below.
Depth (ft) | CBV (ac-ft) | Depth (ft) | CBV (ac-ft) |
---|---|---|---|
9400 | 0.00 | 11,200 | 58866.34 |
9600 | 3159.46 | 11,400 | 64419.35 |
9800 | 11623.16 | 11,600 | 70282.13 |
10,000 | 23833.84 | 11,800 | 76.469.17 |
10,200 | 33547.92 | 12,000 | 82988.40 |
10,400 | 38822.03 | 12,200 | 89843.60 |
10,600 | 43697.74 | 12,400 | 97035.93 |
10,800 | 48568.69 | 12,600 | 104564.78 |
11,000 | 53597.63 |
The following petrophysical and PVT parameters apply: Gas-Oil contact (GOC) = 10,400 ftss; Oil-Water contact (OWC) = 12,200 ftss; oil formation volume factor = 1.3279 rb/stb; Gas expansion factor (Ei) = 185.1 scf/cuft; sand/shale factor (F) = 88%; porosity = 18%; connate water saturation = 13%.
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I.
Indicate on a depth vs CBV plot, the depth at which the oil volume is acting
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II.
Calculate the volume of free-gas initially in place (in MMMscf)
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III.
Calculate the volume of the stock tank oil initially in place (in MMstb)
-
IV.
Calculate the gas cap size, m
-
V.
Find the centroid depth of the reservoir
Ex 3.3
A hydrocarbon reservoir is mapped out in area recorded at corresponding depths as given in the table.
Depth (ftss) | Top Area (acres) | Base Area (acres) |
---|---|---|
8800 | 0.000 | |
9000 | 33.21 | |
9300 | 91.31 | 0.00 |
9400 | 112.64 | 16.20 |
9500 | 125.06 | 32.40 |
9700 | 148.23 | 54.00 |
10,000 | 175.55 | 79.92 |
10,400 | 215.62 | 116.64 |
10,500 | 228.74 | 127.44 |
11,000 | 297.32 | 183.06 |
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I.
Using numerical approximation method, determine (in Mac-ft) the cumulative bulk volume (CBV) down to the OWC
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II.
Find the centroid depth of the reservoir
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III.
Calculate the hydrocarbon pore volume in MMbbls down to the OWC for the following three sets of petrophysical data:
-
(a)
All sand with porosity 21% and connate water saturation of 20%
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(b)
50% productive limestone with porosity 17% and connate water saturation of 30% 50% non-productive
-
(c)
5/8 ths sand as above; 3/8rds limestone as above
-
(a)
Additional Data:
Crest of top reservoir = 8800 ftss; crest of base of reservoir = 9400 ftss; OWC = 10,700 ftss; 1 acres = 7758.4 bbls.
Ex 3.4
Calculate the following with the data given in Table 3.8:
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I.
The gas initially in place
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II.
Gas in place after volumetric depletion to a pressure of 3540 psia
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III.
Gas in place after volumetric depletion to abandonment pressure
-
IV.
Gas in place after water invasion at initial pressure
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V.
Gas in place after water invasion at a pressure of 3540 psia
-
VI.
Gas in place after water invasion at a pressure of 555 psia
-
VII.
Gas produced by full water drive at initial pressure
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VIII.
Recovery factor after full water drive at initial pressure
-
IX.
Gas produced by partial water drive at 3540 psia
-
X.
Recovery factor after partial water drive at 3540 psia
-
XI.
Gas produced by volumetric to abandonment pressure
-
XII.
Recovery factor at abandonment pressure
Ex 3.5
Use the Monte-Carlo techniques to calculate the porosity value from the set of data assuming a uniform probability of 0.89:
0.23, 0.21, 0.20, 0.24, 0.21, 0.205, 0.22, 0.21, 0.22, 0.22, 0.24, 0.235, 0.215, 0.21, 0.23, 0.21, 0.23, 0.23, 0.21, 0.20, 0.21, 0.23, 0.21, 0.20, 0.21, 0.21, 0.23, 0.20, 0.20, 0.21, 0.21, 0.20, 0.20, 0.21, 0.23, 0.23,
For:
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I.
Fixed Value
-
II.
Uniform Distribution
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III.
Triangular Distribution
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IV.
Normal Distribution
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V.
Log Normal Distribution
Ex 3.6
Calculate the gas reserve in a gas field of 2300 acres, with 40 ft. sand thickness, 23% porosity, 17% water saturation, initial pressure of 3200 psi and temperature of 200 °F. the composition of the gas and their weight fractions are as follows: 93.63% methane; 3.54% ethane; 1.46% propane; 0.38% isobutene, 0.36% pentane and 0.17% hexane plus.
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Okotie, S., Ikporo, B. (2019). Volumetric Reserves Estimation. In: Reservoir Engineering. Springer, Cham. https://doi.org/10.1007/978-3-030-02393-5_3
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DOI: https://doi.org/10.1007/978-3-030-02393-5_3
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