Petroleum Geology Problem Set 1 Petroleum Composition 1.
The wetness of a natural gas is an important economic factor in petroleum exploration and
production. Wetness is calculated by:
Wetness ratio= [(C2 + C3 + C4 + C5 + C6+)/(C1 + C2 + C3 + C4 + C5 + C6+)] x 100
For each of the five gas data sets, calculate the numeric “wetness” of each sample.
Based on your class notes, classify these gases as wet, dry, or intermediate.
2.
Natural gas is delivered to a distribution pipeline and sold according a price per mcF (1000
cubic feet) on a BTU basis; the price is set per 900 BTU. A current example is today’s price for
natural gas is $2.17mcF/BTU basis (or per 900 BTU). Use the BTU calculator web sheet (located
on the Carmen webpage) to calculate a) the BTU content of each of the five wells and b) the current
spot price (use the price at close of business 1/27/2016).
3.
A cubic meter of gas contains 28.3169 liters and 35.315 cubic feet. Gas is typically sold in
units of mcf (1000 cubic feet), while 1Mcf=1 million cubic feeet. The production history for each
of your field described in question 1 are included below. A) Calculate the daily, month (30 day
average), and yearly production of total gas in mcf and m3? On a BTU basis, as calculated in
question 2, what is the daily, month, yearly revenue for each field? )? Based on the daily costs of
production and annual fees (which include leases, maintenance, and taxes) shown below, what is
the net revenue for each field? C) Are there any field that should be shut down at this current price?
Rank your performers according to total economic output. D) Calculate the daily, monthly, and
yearly production of C1, C2, C3, C4, and C5 in mcf and m3?
Daily production history of your gas fields.
Field 1: 1.31Mcf/day
Field 2: 932,154mcf/day
Field 3: 0.614Mcf/day
Field 4: 3.152Mcf/day
Field 5: 267,874Mcf/day
Annual additional costs of production history from your fields:
Field 1: $92,100/yr
Field 2: $87,400/yr
Field 3: $32,724/yr
Field 4: $67,987/yr
Field 5: $17,540/yr
4.
Oil is sold to the market by the barrel with a price referenced to archetypal crudes. For
example, West Texas Intermediate (API gravity=45) is often used as the reference barrel in the
US. At your new company, you do not have an API gravity kit, but you can measure specific
gravity. Based on the specific gravity of the five fields your company actively produces a) calculate
the API gravity; b) provide a reasonable estimate of viscosity; c) estimate a sales price referenced
to WTI using today’s spot price; d) based on the following classification scheme classify your
crude oil; and e) rank the quality of the fields in order.
Specific Gravity of crudes from your fields:
Field A: 0.821
Field B: 0.779
Field C: 1.034
Field D: 0.934
Field E: 0.876
5.
A typical unit of crude sales in the US is barrels of oil. Internationally, crude is sold in
either barrels or cubic meters (m3). One cubic meter equals 35.3 cubic feet or 1.3 cubic yards,
while a typical barrels is approximately 222.02993 cubic feet. Now that it is legal to export oil
from the US, your company needs to be able to convert prices and production records to this unit.
a)
how many barrels of oil are produced from each field per month; b) how many barrels per
year; c) how many cubic meters of oil per month; d) how many cubic meters of oil per year; e)
Average production history from your fields:
Field A: 414 barrels/day
Field B: 174 b/d
Field C: 309 b/d
Field D: 163 b/d
Field E: 121 b/d
6.
Using the specific gravity data and API gravity values above, what is the revenue of each
field per month; what is the revenue per year (again using today’s spot price)? Based on the daily
costs of production and annual fees (which include leases, maintenance, and taxes) shown below,
what is the net revenue for each field? Are there any field that should be shut down at this current
price? Rank your performers according to total economic output.
Daily cost of production history from your fields:
Field A: $2604/day
Field B: $1975/d
Field C: $4624/d
Field D: $3259/d
Field E: $2214/d
Annual additional costs of production history from your fields:
Field A: $232,100/yr
Field B: $193,500/yr
Field C: $342,684/yr
Field D: $105,146/yr
Field E: $401,000/yr