This paper introduces the research methods of initial oil production of new wells, economic limit water cut and economic limit oil production of old wells, and the economic policy boundaries of oil increase measures, and makes the development economic policy boundary maps of different types of oilfields in Shengli Oilfield, which provides a basis for avoiding invalid workload and improving the overall economic benefits of oilfield development.
Key words: economic policy boundary, economic limit water cut measures, economic limit oil production and economic benefit Shengli oil region
I. Introduction
In the process of oilfield development, with the increase of water content and development difficulty, its output will continue to decline. When the output is reduced to a certain limit and its output value cannot balance the necessary investment and cost, the exploitation of oil fields or oil wells will be inefficient or even lose money. Therefore, it is of great significance to study the economic policy boundary of oilfield development for improving the economic benefits of oilfield development.
1. Calculation principle and method
Second, the economic limit of initial oil production in new wells
The economic limit initial oil production of a new well refers to the corresponding oil production when the cumulative output value of the oil well in the payback period is equal to the sum of the total investment, accumulated annual operating expenses and necessary taxes, that is, the economic benefit of a single well in the payback period is zero, which is called the economic limit initial oil production of a new well.
The economic benefits of single well investment payback period are as follows
Essay on exploration and development in Shengli oil region
When the cumulative economic benefit of payback period is 0, that is, Pp=0, the calculation formula of initial oil production of new well economic limit is as follows
Essay on exploration and development in Shengli oil region
Where: PP-cumulative benefit of a single well during the payback period, 104 yuan;
Sp—— Total output value of production wells during the investment recovery period, 104 yuan;
K—— cumulative total investment of a single well during the payback period, 104 yuan;
Cp—— the annual cumulative operating cost of a single well during the payback period, 104 yuan;
τ 0-well opening, decimal;
Qmin-economic limit initial oil production of new wells and single wells, t/d;
W-crude oil commodity price, decimal;
P—— crude oil price, RMB/ton;
RT-tax per ton of oil, RMB/ton;
T—— payback period of investment, a;
B—— the annual declining surplus rate of oil well production during the investment payback period, in decimal;
I B- single well surface construction investment, 104 yuan/well;
ID- single well drilling investment, 104 yuan/well;
β-coefficient of oil-water well, decimal;
I-annual growth rate of operating costs, in decimal;
C0-single well operation cost, 104 yuan/well.
2. Determination of parameters [1]
(1) investment
Investment can be divided into two parts: drilling investment and surface construction investment.
Drilling investment refers to the investment in development wells drilled in the process of oil and gas field development and construction, including investment in pre-drilling preparation engineering, drilling engineering, logging and completion engineering. Its investment amount is mainly related to well depth. There is the following regression formula between drilling investment CM per meter and well depth h in Shengli Oilfield (excluding offshore oilfield).
Essay on exploration and development in Shengli oil region
The investment in oilfield surface construction mainly includes oil and gas gathering and transportation, water injection, water supply and drainage, power supply, communication and roads. According to the actual investment in oilfield surface construction during the Ninth Five-Year Plan period, the average single well surface construction investment can be determined for new wells in old areas, new wells in new areas and offshore oil wells.
(2) Operating costs and expenses
Operating costs and expenses are the sum of all kinds of consumption and expenses incurred by oil and gas field enterprises in their production and operation activities, including oil and gas exploitation costs, management expenses, sales expenses and financial expenses. The cost of crude oil exploitation includes direct materials, direct wages and other direct expenses actually consumed in the production process. Management, sales and financial expenses incurred in the process of oil and gas exploration and development are directly deducted from the current sales income as current profits and losses.
According to the current accounting statement, the oil and gas exploitation cost consists of 65,438+05 items, including power cost, material cost, fuel cost, production personnel salary, welfare cost, oil displacement and injection cost, thermal recovery cost, oil and gas treatment cost, light hydrocarbon recovery cost, downhole operation cost, well logging and well testing cost, repair cost, manufacturing cost, loss and amortization cost and exploration cost.
(3) Taxation
The main taxes are value-added tax, urban construction tax, education surcharge tax, resource tax and so on. In order to simplify the steps, the comprehensive tax per ton of oil under different oil prices is calculated. When the price of crude oil is 800 ~ 1800 yuan /t, the comprehensive tax per ton of oil is 99 ~ 220 yuan/t.
(4) Decline rate
In order to determine the production decline rate of new wells, the change law of new wells in Shengli oil region 1990 ~ 1995 is statistically analyzed, and the daily oil production level is divided into five grades: less than 4t, 4-6t, 6-8t, 8- 10t and greater than 10t. The statistical results show that the decline rate is related to the initial oil production of a single well, and the higher the initial oil production of a single well, the greater the decline rate. The decline rate of single wells with initial oil production greater than 10t/d is about 15%, and the decline rates of single wells with initial oil production of 8 ~ 10t/d, 6 ~ 8t/d and 4 ~ 6t/d are 12% and/kloc-0, respectively.
3. Calculation of economic limit initial oil production of new wells
Based on the analysis of the investment and cost since the Ninth Five-Year Plan in Shengli Oilfield, combined with the changing law of daily oil production of a single well, the economic limit initial oil production of new wells in the old land area, the new land area and the new Shanghai area under different well depths and different oil prices are calculated respectively.
According to the calculated economic limit initial oil production, the new blocks in Shengli Oilfield since the Ninth Five-Year Plan are evaluated, and on the basis of comprehensive analysis, the proportion of inefficient production in different blocks under different oil prices is obtained.
(1) Calculation of initial oil production of new wells in onshore new area
Based on the conditions of well depth 1 000 ~ 3500m and crude oil price of 900 ~ 1700 yuan/ton, the economic limit initial oil production of new wells in low-permeability oil fields and high-permeability oil fields in the new onshore area is calculated and plotted (Figure1and Figure 2). As can be seen from the figure, when the well depth is the same, the higher the oil price, the lower the economic limit initial oil production of the new well; Under the same oil price, the shallower the well, the lower the requirement for the initial oil production of the new well.
Figure 1 Initial oil production of new wells in low permeability oilfield in onshore new area
Fig. 2 Economic Limit Initial Oil Production of New Wells in High Permeability Oilfield in New Land Area
The initial production requirement of new wells in high permeability oilfield is lower than that in low permeability oilfield. When the oil price is 1000 yuan/ton and the well depth is 2000 meters, the economic limit initial production of new wells in high permeability oilfield is 5.65 tons/day, and that in low permeability oilfield is 6. 12 tons/day.
According to the economic limit initial oil production map of new wells in onshore new area, the new wells in onshore new area 1996 ~ 1998 in Shengli Oilfield are tracked and analyzed. 17 new wells were drilled in the new area in 1996, with an average single well production of 1 1.43t/d, including 78 inefficient wells, with an average single well production of 3.35t/d, and the number of inefficient wells accounted for 24.6%, but the output only accounted for 4./kloc-. The inefficient wells of 1997 and 1998 accounted for 25.6% and 20.2% of the newly drilled wells in that year, respectively, and the production accounted for 6. 1% and 3.5% respectively.
(2) Calculation of initial oil production of new wells in old areas.
The well depth in the old land area is 1000 ~ 3500m, the crude oil price is 900 ~ 1700 yuan /t, and the calculation results of the economic limit of new wells in low permeability and high permeability oilfields are shown in Figure 3 and Figure 4 respectively. Because the drilling investment, surface construction investment and operation cost of low permeability oilfield are higher than those of high permeability oilfield, the economic limit initial oil production of new wells is higher than that of high permeability oilfield. When the oil price is 1000 yuan/ton and the well depth is 2000 meters, the economic limit initial production of new wells in high permeability oilfield is 5.3t/d and that in low permeability oilfield is 5.5t/d. ..
Fig. 3 Economic Limit Initial Oil Production of New Wells in Old Low Permeability Oilfield
Fig. 4 Economic Limit Initial Oil Production of New Wells in Old High Permeability Oilfield
According to the economic limit initial oil production map of new wells in the old area, the new wells in the old area have been tracked and analyzed since Shengli Oilfield 1990, and the proportion of inefficient production of new wells under different oil prices has been obtained. When the oil price is 1 1,000 yuan /t, the inefficient production ratio of new wells in the old area rises from 4.5% to 13.4%, which is higher than that of new wells in the new area, and the inefficient production ratio rises rapidly. After 1995, the new well location design was continuously optimized by applying new technologies such as fine reservoir description, so that the rising trend of ineffective production ratio was controlled and basically maintained at around 13%.
(3) Calculation of initial oil production of new wells in offshore oilfield.
According to the analysis results of economic parameters of offshore oil fields, the initial oil production of new wells in offshore oil fields with different oil prices and different well depths is calculated and plotted (Figure 5). When the price of crude oil is 1000 yuan/ton, the economic limit initial oil production of new wells in offshore oilfield is 35.7 tons/day (well depth is 2200m). 1999, the average selling price of crude oil in Shengli Oilfield was 93 1 yuan /t, and the corresponding economic limit initial oil production of new offshore wells was 36t/d. ..
Fig. 5 Economic Limit Initial Oil Production of New Wells in Offshore Oilfield
According to the above-mentioned economic limit initial production, the proportion of inefficient production of new wells in offshore oil fields in recent years is counted. When the oil price is 1 1,000 yuan /t, the ineffective production ratios of 1, 995 ~ 1, 998 are 1.08%, 7.87%, 4.36% and 7.36% respectively. Since Guantao Formation reservoir in Haibei Oilfield was put into full production from 1995 to 1996, new technologies such as seismic constrained inversion and reservoir protection have been continuously applied to optimize the scheme design, resulting in a high drilling success rate and a significant decrease in the inefficient production ratio of new wells. With the increasing difficulty of reserves utilization, the proportion of inefficient production increases after 1998.
Three, the old well economic limit water content and economic limit oil production
Studying the economic limit water cut and economic limit oil production of an oilfield can identify inefficient wells in time and take measures such as shut-in, injection transfer and layer adjustment to improve economic benefits.
1. Calculation principle and method
Economic limit water cut and economic limit oil production mean that when an oil field (oil well) develops to a certain stage, the water cut rises to a certain value or the oil production drops to a certain value, and the input and output reach a balance. If the water cut rises again and the oil production drops again, there will be no profit in oilfield development. The water content of an oil field (oil well) at this time is called economic limit water content, and its corresponding output is called economic limit production.
The principle of break-even is used to calculate the economic limit water cut of old wells and the economic limit initial oil production of new wells, but the difference is that the calculation of the economic limit initial oil production of new wells refers to the input-output balance at a certain stage (payback period), while the calculation of the economic limit water cut of old wells refers to the instantaneous input-output balance (generally one year).
Because the old well is generally considered to have experienced more than 8 years of mining time, when calculating the economic limit water cut and economic limit oil production of the old well, its investment can be ignored and only its operating cost can be calculated. Different concepts of economic limit water content and economic limit oil production can be obtained by different consideration methods of crude oil operation cost. The conventional cost analysis method is to consider all the operating costs required for the exploitation of old wells; The lowest cost analysis method is calculated according to the main cost of maintaining oil well production.
The input-output balance formula for calculating the economic limit water content and economic limit oil production of old wells is:
Essay on exploration and development in Shengli oil region
Formula (4) can be used to derive the expressions for calculating the economic limit water cut and economic limit oil production of old wells:
Essay on exploration and development in Shengli oil region
Where: qo, minimum economic limit oil production, t/d;
Fw, minimum economic limit water content, decimal;
QL-single well fluid production, t/d;
CV-variable cost per ton of liquid, yuan/ton;
CG- fixed cost, 104 yuan/well;
T-the number of years between the forecast year and the base year, a
2. The relationship between the cost per ton of liquid and the average single well liquid production.
Single well production costs are divided into fixed costs and variable costs. (5) and (6), it is very important to accurately calculate the production cost of a single well. In order to improve the operability and practicability of this method, the production cost of a single well can be calculated directly from the average liquid production and the cost per ton of liquid by studying and simplifying the cost analysis project.
According to the statistical analysis of the lowest cost, the liquid cost CL of 40 onshore water drive development oilfields in Shengli Oilfield is well correlated with the average single well liquid production qL, and the regression relationship is as follows:
Essay on exploration and development in Shengli oil region
Substituting Formula (7) into Formulas (5) and (6), new expressions of economic limit oil production and economic limit water content can be obtained:
Essay on exploration and development in Shengli oil region
3. Calculation of economic limit oil production and economic limit water content of old wells
(1) Calculation of economic limit oil production and economic limit water content of old wells on land
Oil price is 800 ~ 2,400 yuan /t, single well liquid production 10 ~ 160t/d, and the economic limit oil production and economic limit water cut of old wells are calculated by formulas (8) and (9) (Figures 6 and 7). It can be seen from the figure that the higher the oil price, the lower the economic limit oil production of a single well under the same liquid production conditions. At the same oil price, the higher the liquid production of a single well, the higher the economic limit oil production of a single well. When the oil price is 1000 yuan /t and the single well liquid production is 10t/d, the economic limit oil production of single well is 1. 15t/d, and the economic limit water cut is 88.5%. When the liquid production of a single well is 160t/d, the economic limit oil production of a single well is 1.68t/d, and the economic limit water cut is 98.9%.
(2) Calculation of economic limit water content and economic limit oil production of old offshore wells.
Due to the limitation of data, the relationship between ton liquid cost and single well liquid production has not been established in offshore oil fields, and its crude oil cost is obtained by item-by-item statistics. Using formulas (5) and (6), when the oil price is 1 1,000 yuan /t and the liquid production of a single well is 30t/d, it is calculated that the economic limit water cut of the old well is 87.2% and the economic limit oil production is 3.8t/d; When the liquid production of a single well is 80t/d, it is calculated that the economic limit water cut of the old well is 89. 1% and the economic limit oil production is 8.7t/d. From the calculation results, due to the high production cost of crude oil, the economic limit water cut of offshore oil fields is much lower than that of onshore oil fields, while the economic limit production is much higher than that of onshore oil fields.
(3) Situation of old wells and inefficient wells in Shengli Oilfield
According to the discriminant diagram of economic limit oil production and economic limit water cut of old wells, 13028 old wells drilled in June 2000 were analyzed, among which 1293 wells were inefficient, accounting for 9.9% of the total number of wells. The monthly oil production is 1.94× 104t, accounting for 0.83% of all old wells. The average daily oil production per well is 0.5t；; The comprehensive water content is 98.2%. The lowest production cost of these inefficient wells in June 2000 was 3365× 104 yuan, the year-on-year output value was 1982× 104 yuan, and the loss was 1383× 104 yuan. It is suggested that this part of the well be shut in and transferred to other wells.
Fig. 6 Economic limit oil production of old wells on land
Fig. 7 Economic Limit Water Cut of Old Well
Fourth, measures to increase oil production economic boundaries [2]
1. Calculation principle and method
The economic limit of oil production by measures is the cumulative oil production after measures and before measures when the input and output of oil wells are balanced within the effective period of measures, and its calculation formula is:
Essay on exploration and development in Shengli oil region
In which: IC- new investment for measures, 104 yuan;
TC—— the effective period of measures, a;
Cc—— cost of measures, RMB/ton;
Qc—— economic limit of measures to increase oil, t/d
2. Calculation example
The formula (10) is used to calculate the economic limit of increasing oil production by five measures: running electric pump, sand control, repairing hole and changing layer, running large pump and plugging. The effective period of electric pump operation measures is six months to two years, the limit value of increasing oil per well is 2.29 ~ 0.57 t, and the cumulative economic limit value of increasing oil is 364 t; The cumulative economic limit values of oil increase for sand control, hole patching and layer modification, running large pumps and plugging are11t, 158t, 95t and 142t respectively.
Verb (abbreviation of verb) Economic limit oil-steam ratio of heavy oil steam huff and puff thermal recovery wells
1. Calculation principle and method
Heavy oil steam injection production requires higher equipment and technology than thin oil production, with higher equipment investment and higher crude oil cost. Therefore, special attention should be paid to the economic boundary when developing steam huff and puff thermal recovery wells. When the oil-steam ratio reaches a certain value, so that the total cost is higher than the total sales revenue, steam injection mining has no economic significance, and the oil-steam ratio at the break-even point is the economic limit oil-steam ratio.
The calculation formula of economic limit oil-steam ratio is:
Essay on exploration and development in Shengli oil region
Where: osrmin-economic limit oil-gas ratio, decimal;
CIG—— the average cost of each injection of 1m3 steam, yuan/m3;
CWDF—— Average shared fixed cost of a single well, yuan/day;
CG-variable cost per ton of oil, RMB/ton;
Qo- average single well oil production, t/d.
2. Calculation example
According to the actual cost of Gudao Oilfield 1998 heavy oil, the related expenses of steam injection are calculated according to the steam injection fee and part of thermal recovery fee. When the daily output of a single well in Gudao heavy oil field is 4t, 5.2t, 6t, 7t, 8t and 10t respectively according to the formula (165438), and the oil price is 948 yuan /t,
Conclusion of intransitive verbs
In this paper, the cost and investment classification of different types of oil reservoirs are analyzed and studied, and the functional relationship between the ton liquid cost of old wells and the liquid production of single wells is established, which simplifies the calculation method and steps of the economic limit water cut of old wells and improves the practicability of the method.
The economic limit values of new wells, old wells, thermal recovery wells and measure wells are comprehensively and systematically studied, and the economic limit maps of different types of oilfield development in Shengli Oilfield are made, which provides a basis for shutting down and converting inefficient and ineffective wells.
Acknowledgement This paper focuses on the main achievements of the Development Comprehensive Planning Office of the Academy of Geological Sciences in economic policy boundary in recent years, which is the crystallization of collective wisdom. Sun Huanquan, deputy chief geologist of Shengli Co., Ltd. and president of Geological Institute, and Fang Kaipu, chief geologist of Development Management Department, gave careful guidance. Other participants in this thesis are Fan, Gao, Wu Zuozhou, Hou Chunhua, Wang Xing, etc. I want to thank all of them.
Main references
[1] Planning Bureau of China Petroleum Corporation, editor of Planning Institute of China Petroleum Corporation. Economic evaluation methods and parameters of petroleum industry construction projects (second edition). Beijing: Petroleum Industry Press, 1994.
Li Yue, Yue Dengtai. Economic evaluation method of recoverable reserves in high water cut stage of old oilfield and measures to increase production. Acta petrolei sinica, 2000,21(5).