Novel economic coupling method for multi-section fractured horizontal well engineering technology

Abstract

The invention relates to a novel economic coupling method for a multi-section fractured horizontal well engineering technology. The defects that domestic gas field drilling and fracturing investment is too large, manpower is wasted, and an economic evaluation method is not meticulous are overcome at present. According to the technical scheme, the method comprises the steps of inputting geological and engineering parameters to predict annual yields corresponding to different horizontal segment lengths with 21 years as a cycle, inputting economic parameters to calculate cash inflow, cash outflow and enterprise income tax, converting to a construction period of the first year according to a discount cash flow method to calculate a net present value, and obtaining a coupling chart of the net present value, the fracturing segment number and the horizontal segment lengths;

Description

Technical Field

[0001] The invention relates to optimization of horizontal section length, number of fracturing sections and economic evaluation method of a multi-section fracturing horizontal well, and belongs to the field of gas reservoir engineering. Background Art

[0002] Multi-stage fracturing horizontal well technology and gas well economic evaluation are important technologies widely used in gas reservoir development. The horizontal section length and the number of fracturing stages of horizontal wells are one of the important issues in horizontal well development and design. The horizontal section length and the number of fracturing stages not only affect the horizontal well leakage area, single well production, and drilling and completion costs, but also affect the number of drilling and investment plans for oil and gas reservoirs.

[0003] It is often believed that the longer the horizontal section, the better. The number of fracturing stages is related to the length of the horizontal section. Using a longer horizontal section length can achieve a higher recovery factor and oil production rate, but the cost will inevitably increase accordingly. Using a smaller horizontal section length can reduce the cost, but it will affect the gas production rate and the final recovery factor. Therefore, there must be a reasonable horizontal section length of the horizontal well and a reasonable number of fracturing stages. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of excessive investment in domestic gas field drilling and fracturing, waste of manpower, and imprecise economic evaluation methods.

[0005] To achieve the above object, the present invention provides a new method for coupling engineering technology and economy of multi-stage fracturing horizontal wells, which includes the following steps:

[0006] S100: By deriving the relationship model between gas reservoir seepage, horizontal section flow, horizontal well production and horizontal section length, a development technology index model is established. The gas reservoir seepage model is as follows: The horizontal flow model is as follows: The coupling model of gas reservoir seepage and horizontal flow is shown in Eq. The relationship model between horizontal well productivity coefficient and horizontal section length is as follows: in A=d*(L+200),γ=Φ*h*S g , where formation pressure p e (MPa), bottom hole pressure pwf (MPa), formation thickness h (m), channel width d (m), formation temperature T (K), horizontal section length L (m), horizontal wellbore radius r w (m), number of fracturing stages N (stages), crack length L f (m), permeability K (mD), porosity Φ, gas saturation S g , standard natural gas temperature T sc (K), natural gas deviation factor Z, gas viscosity μ g (MPa·s).

[0007] S200: A physical model consisting of hydraulic fractures + microfractures + matrix pores is established. It is assumed that the reservoir is composed of matrix pores, natural microfractures and hydraulic fractures. The injected fracturing fluid enters the microfractures and hydraulic fractures but not the matrix pores. However, the fracturing fluid in the microfractures cannot be produced during production, and the fracturing fluid in the hydraulic fractures is returned. The gas in the matrix pores diffuses into the microfractures, and the tight gas in the microfractures flows into the hydraulic fractures in the form of single-phase Darcy seepage. The tight gas in the hydraulic fractures flows into the wellbore in the form of gas-liquid two-phase Darcy seepage.

[0008] S300: Inflows from gas well production include operating income (C r ), output tax (C s ) and recover working capital (C R ), operating income is the sales of natural products, the formula is as follows: C r (t) = Q(t)P, where the operating income in the tth year is C r (t) (10,000 yuan), annual output in year t Q (t) (10 4 m 3 / a), sales price of produced natural gas P (10,000 yuan / 10 4 m 3 ), the output tax is the VAT amount calculated based on the sales volume and the applicable tax rate and charged to the purchaser, the formula is as follows: C s (t) = C r (t)r VAT , where the output tax amount in year t is C s (t) (10,000 yuan), operating income in year t C r (t) (10,000 yuan), natural gas value-added tax rate r VAT , the recovery of working capital is the recovery of the operating capital originally invested in various current assets at the end of the project calculation period. The formula is as follows: C R (t)=(C o (t)-C o (t-1))r LR , where the working capital C is recovered in the tth year R (t) (10,000 yuan), operating cost in year t C o (t) (10,000 yuan), liquidity ratio r LR .

[0009] Outflows from gas well production include investment (C i )、Liquidity (C1)、VAT (C VAT ), taxes and surcharges (C t ), operating costs (C o ), cost input tax (C IT ) and disposal costs (C d), the investment is calculated based on pre-drilling engineering, drilling engineering (including the drilling cost per meter of the horizontal section), oil testing engineering (including fracturing costs), other costs and ground sharing, and the format is as follows: C i =C in (r vdp +1), where construction investment C in (10,000 yuan), VAT deduction ratio vdp , working capital is the manifestation of current assets, the formula is as follows: C1(t) = (C o (t)-C o (t-1))r LR , where the working capital C in the tth year R (t) (million yuan), operating cost Co(t) (million yuan), working capital ratio r LR , when a general VAT taxpayer makes VAT-taxable sales or imports goods, the formula is as follows: C VAT (t)=(C s (t)-C IT (t)-C Vc (t)), where the output tax amount in year t is C s (t) (10,000 yuan), input tax on cost in year t C IT (t) (ten thousand yuan), the amount of VAT deduction in the tth year C Vc (t) (ten thousand yuan), the disposal cost is the undiscounted disposal cost, the formula is as follows: C d =C i r d , investment C i (10,000 yuan), the proportion of undiscounted disposal cost to total investment d , operating costs refer to the cost of goods sold or services provided by the enterprise, and the formula is as follows: C o (t) = Q(t)r c r oc +Q(t)r s +Q(t)r c r m +C r (t)r oe , where the natural gas commodity rate r c , operating cost oc (10,000 yuan / 10 4 m 3 ), natural gas safety production costs s (10,000 yuan / 10 4 m 3 ), other management fees m (10,000 yuan / 10 4 m 3 ), operating expenses as a percentage of revenue oe , the cost input tax formula is as follows: CIT (t) = Q(t)r Vi r oc r inc , where cost input tax VAT rate r Vi , operating cost oc (10,000 yuan / 10 4 m 3 ), input tax ratio of operating cost inc , taxes and surcharges include urban maintenance and construction tax, education surcharge, resource tax, special oil revenue and mining rights transfer revenue, the formula is as follows: C t (t) = C VAT (t)r U +C VAT (t)r e +C r (t)r R +C ps (t)+C r (t)r m , where the urban maintenance and construction tax rate is r U , Educational surcharge rate e , Special oil revenue in year t C ps (t) (10,000 yuan), actual collection rate of resource tax on crude oil and natural gas R , Mining rights transfer rate of return r m .

[0010] S400: Enterprise income tax calculation formula: CT(t) = C r (t)-C t (t)-C o (t)-C ga (t)-C dc (t), where the corporate income tax CT(t) (10,000 yuan) in the tth year and the operating income C r (t) (ten thousand yuan), tax and surcharge for year t t (t) (10,000 yuan), operating cost in year t C o (t) (10,000 yuan), depreciation of oil and gas assets in year t C ga (t) (10,000 yuan), the depreciation of the disposal cost in the tth year C dc (t) (million yuan), the formula for depreciation of oil and gas assets and depreciation of abandonment costs is as follows: C ga (t)+C dc (t)=(C in +C d )r wr (t), where the depreciation rate in year t is r wr (t).

[0011] S500: Using the discounted cash flow method, combined with the gas well development effect, the classic indicator net present value (NPV) is selected to evaluate the benefits of the implemented single well, as shown in the formula Wherein, the net present value NPV of gas well production (10,000 yuan), cash inflow CI (10,000 yuan), cash outflow CO (10,000 yuan), corporate income tax CT (10,000 yuan), calculation period n (years), and benchmark rate of return i.

[0012] S600: With the capacity coefficient and output as the link and the net present value benefit parameter as the target, the technical indicator model and the economic evaluation model are coupled to obtain the technical and economic evaluation model. The fracturing engineering technical parameters, engineering technical limits and economic limits such as the horizontal section length and the number of fracturing sections of multi-stage fracturing horizontal wells are coupled and analyzed. The calculation model of the economic optimal length of the horizontal section of multi-stage fracturing horizontal wells and the economic optimal number of fracturing sections of multi-stage fracturing horizontal wells is established. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the attached picture:

[0014] Figure 1 Method technology roadmap;

[0015] Figure 2 Production forecast chart;

[0016] Figure 3 Cumulative cash flow diagram before income taxes;

[0017] Figure 4 Cumulative cash flow diagram after income taxes;

[0018] Figure 5 NPV, number of fracturing stages and horizontal section length coupling chart; DETAILED DESCRIPTION

[0019] According to the following Figure 1 The technical route and preferred embodiments of the present invention are described in detail, and the method comprises the following steps:

[0020] Step 1: Bring in the geological and engineering data in Table 1 and establish a development technology indicator model through S100. The model couples the horizontal section length and the number of fracturing stages.

[0021] Table 1 Geological and engineering parameters

[0022] Parameter name Value unit Gas reservoir thickness 22 m Porosity 9.5 ％ Saturation 65 ％ Permeability 0.5 mD Supply boundary pressure 27 Mpa Formation temperature 66 ℃ River width 800 m Horizontal wellbore radius 0.106 m Fracturing stages 10 part Liquid addition intensity 24.61 <![CDATA[m 3 / m]]>

[0023] Step 2: Figure 2 For example, through S200, the output is predicted with a 1-year construction period and a 20-year production period as the evaluation cycle. In the first year of construction, there is no production and no output.

[0024] Step 3: Figure 3For example, through S300, substitute the economic data in Table 2 to calculate the cash inflow and cash outflow. The net cash flow before income tax is the cash inflow minus the outflow. The cumulative net cash flow before income tax is calculated cumulatively.

[0025] Table 2 Economic data

[0026] Evaluation parameters Value Evaluation parameters Value <![CDATA[Natural gas price (10,000 yuan / 10 4 m 3 )]]> 1.375 Input tax ratio of operating costs 0.3 <![CDATA[Natural gas production safety cost (10,000 yuan / 10 4 m 3 )]]> 0.0075 <![CDATA[Other management fees (in ten thousand yuan per 10 4 m 3 )]]> 0.05 Industry benchmark yield 8％ Natural Gas Commodity Rate 98％ Natural gas VAT rate 10％ Condensate production cost (10,000 yuan / 10,000 tons) 22 VAT rate for condensate 13％ Mining rights transfer rate of return 0.9％ Cost input tax VAT rate 11％ Liquidity ratio 0.25 Urban maintenance and construction tax rate 8％ Undiscounted disposal costs as a percentage of total investment 0.06 Educational surcharge rate 6％ Net residual value of oil and gas assets 0 Actual collection rate of resource tax on crude oil and natural gas 5.8％ Undiscounted disposal costs as a percentage of total investment 0.06 <![CDATA[Operating cost (10,000 yuan / 10 4 m 3 )]]> 0.291 Construction investment loan interest rate 5％ Operating expenses as a percentage of revenue 0.0045 Income tax rate 15％、25％

[0027] Step 4: Figure 4 For example, through S400, the corporate income tax is calculated by subtracting the corporate income tax from the net cash flow before the income tax to obtain the cumulative net cash flow after the income tax.

[0028] Step 5: Use S500 and the discounted cash flow method to convert the net cash flow after income tax to the first year, which is the construction period.

[0029] Step 6: Figure 5 For example, through S600, with the capacity coefficient and production as the link, the horizontal section length of multi-stage fracturing horizontal wells, the number of horizontal well fracturing sections and other fracturing engineering technical parameters, engineering technical limits and economic limits are coupled and analyzed to obtain the coupling chart of net present value, number of fracturing sections and horizontal section length. Point Q in the figure corresponds to the optimal horizontal section length and the optimal number of fracturing sections.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) It is a new intelligent control method that is fast, convenient and accurate, and is easy to understand and promote; (2) It can be directly applied on site to reduce manual intervention; (3) It can adjust parameters according to the actual situation on site, and is highly intelligent.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A new method for coupling engineering technology and economy of multi-stage fracturing horizontal wells, characterized in that: The method comprises the following steps: S100: By deriving the relationship model between gas reservoir seepage, horizontal section flow, horizontal well production and horizontal section length, a development technology index model is established. The gas reservoir seepage model is as follows: The horizontal flow model is as follows: The coupling model of gas reservoir seepage and horizontal flow is shown in Eq. The relationship model between horizontal well productivity coefficient and horizontal section length is as follows: in A=d*(L+200),γ=Φ*h*S g , where formation pressure p e (MPa), bottom hole pressure p wf (MPa), formation thickness h (m), channel width d (m), formation temperature T (K), horizontal section length L (m), horizontal wellbore radius r w (m), number of fracturing stages N (stages), crack length L f (m), permeability K (mD), porosity Φ, gas saturation S g , standard natural gas temperature T sc (K), natural gas deviation factor Z, gas viscosity μ g (MPa·s); S200: Establish a physical model consisting of hydraulic fractures + microfractures + matrix pores. It is assumed that the reservoir is composed of matrix pores, natural microfractures and hydraulic fractures. The injected fracturing fluid enters the microfractures and hydraulic fractures but not the matrix pores. However, during production, the fracturing fluid in the microfractures cannot be produced, and the fracturing fluid in the hydraulic fractures is returned. The gas in the matrix pores migrates to the microfractures in the form of diffusion. The tight gas in the microfractures flows to the hydraulic fractures in the form of single-phase Darcy seepage. The tight gas in the hydraulic fractures flows to the wellbore in the form of gas-liquid two-phase Darcy seepage. S300: Inflows from gas well production include operating income (C r ), output tax (C s ) and recover working capital (C R ), operating income is the sales of natural products, the formula is as follows: C r (t) = Q(t)P, where the operating income in the tth year is C r (t) (10,000 yuan), annual output in year t Q (t) (10 4 m 3 / a), sales price of produced natural gas P (10,000 yuan / 10 4 m 3 ), the output tax is the VAT amount calculated based on the sales volume and the applicable tax rate and charged to the purchaser, the formula is as follows: C s (t) = C r (t)r VAT , where the output tax amount in year t is C s (t) (10,000 yuan), operating income in year t C r (t) (10,000 yuan), natural gas value-added tax rate r VAT , the recovery of working capital is the recovery of the operating capital originally invested in various current assets at the end of the project calculation period. The formula is as follows: C R (t)=(C o (t)-C o (t-1))r LR , where the working capital C is recovered in the tth year R (t) (10,000 yuan), operating cost in year t C o (t) (10,000 yuan), liquidity ratio r LR ; Outflows from gas well production include investment (C i )、Liquidity (C1)、VAT (C VAT ), taxes and surcharges (C t ), operating costs (C o ), cost input tax (C IT ) and disposal costs (C d ), the investment is calculated based on pre-drilling engineering, drilling engineering (including the drilling cost per meter of the horizontal section), oil testing engineering (including fracturing costs), other costs and ground sharing, and the format is as follows: C i =C in (r vdp +1), where construction investment C in (10,000 yuan), VAT deduction ratio vdp , working capital is the manifestation of current assets, the formula is as follows: C1(t) = (C o (t)-C o (t-1))r LR , where the working capital C in the tth year R (t) (million yuan), operating cost Co(t) (million yuan), working capital ratio r LR , when a general VAT taxpayer makes VAT-taxable sales or imports goods, the formula is as follows: C VAT (t)=(C s (t)-C IT (t)-C Vc (t)), where the output tax amount in year t is C s (t) (10,000 yuan), input tax on cost in year t C IT (t) (ten thousand yuan), the amount of VAT deduction in the tth year C Vc (t) (ten thousand yuan), the disposal cost is the undiscounted disposal cost, the formula is as follows: C d =C i r d , investment C i (10,000 yuan), the proportion of undiscounted disposal cost to total investment d , operating costs refer to the cost of goods sold or services provided by the enterprise, and the formula is as follows: C o (t) = Q(t)r c r oc +Q(t)r s +Q(t)r c r m +C r (t)r oe , where the natural gas commodity rate r c , operating cost oc (10,000 yuan / 10 4 m 3 ), natural gas safety production costs s (10,000 yuan / 10 4 m 3 ), other management fees m (10,000 yuan / 10 4 m 3 ), operating expenses as a percentage of revenue oe , the cost input tax formula is as follows: C IT (t) = Q(t)r Vi r oc r inc , where cost input tax VAT rate r Vi , operating cost oc (10,000 yuan / 10 4 m 3 ), input tax ratio of operating cost inc , taxes and surcharges include urban maintenance and construction tax, education surcharge, resource tax, special oil revenue and mining rights transfer revenue, the formula is as follows: C t (t) = C VAT (t)r U +C VAT (t)r e +C r (t)r R +C ps (t)+C r (t)r m , where the urban maintenance and construction tax rate is r U , Educational surcharge rate e , Special oil revenue in year t C ps (t) (10,000 yuan), actual collection rate of resource tax on crude oil and natural gas R , Mining rights transfer rate of return r m ; S400: Enterprise income tax calculation formula: CT(t) = C r (t)-C t (t)-C o (t)-C ga (t)-C dc (t), where the corporate income tax CT(t) (10,000 yuan) in the tth year and the operating income C r (t) (ten thousand yuan), tax and surcharge for year t t (t) (10,000 yuan), operating cost in year t C o (t) (10,000 yuan), depreciation of oil and gas assets in year t C ga (t) (10,000 yuan), the depreciation of the disposal cost in the tth year C dc (t) (million yuan), the formula for depreciation of oil and gas assets and depreciation of abandonment costs is as follows: C ga (t)+C dc (t)=(C in +C d )r wr (t), where the depreciation rate in year t is r wr (t); S500: Using the discounted cash flow method, combined with the gas well development effect, the classic indicator net present value (NPV) is selected to evaluate the benefits of the implemented single well, as shown in the formula In the formula, the net present value of gas well production NPV (10,000 yuan), cash inflow CI (10,000 yuan), cash outflow CO (10,000 yuan), corporate income tax CT (10,000 yuan), calculation period n (years), and benchmark rate of return i; S600: With the capacity coefficient and output as the link and the net present value benefit parameter as the target, the technical indicator model and the economic evaluation model are coupled to obtain the technical and economic evaluation model. The fracturing engineering technical parameters, engineering technical limits and economic limits such as the horizontal section length and the number of fracturing sections of multi-stage fracturing horizontal wells are coupled and analyzed. The calculation model of the economic optimal length of the horizontal section of multi-stage fracturing horizontal wells and the economic optimal number of fracturing sections of multi-stage fracturing horizontal wells is established.

2. A new method for coupling engineering technology and economy of multi-stage fracturing horizontal wells according to claim 1, characterized in that: The specific judgment conditions for obtaining the optimal horizontal section length and the optimal number of fracturing sections in the S600 are as follows: the annual output of each horizontal section length for 20 years is calculated according to the production capacity model and an economic evaluation is performed to obtain a curve of the relationship between the net present value and the horizontal section length. The horizontal section length corresponding to the highest point is the optimal horizontal section length. The number of fracturing sections and the fracturing cost are added to obtain the optimal number of fracturing sections and the optimal horizontal section length under this condition through coupling.

Images