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US-12624624-B2 - Method of artificially assisted filling for sand control and water control of fractured reservoir and method for evaluating filling effect

US12624624B2US 12624624 B2US12624624 B2US 12624624B2US-12624624-B2

Abstract

The present invention belongs to the technical field of oil and gas engineering, and discloses a method of artificially assisted filling for sand control and water control of a fractured reservoir and a method for evaluating a filling effect. The method of artificially assisted filling for sand control and water control of the fractured reservoir comprises the steps: S11, calculating a fracture productivity evaluation index F of the fractured reservoir; S12, calculating an implementation feasibility index G of an artificially assisted filling process; S13, based on the fracture productivity evaluation index F obtained in step S11 and the implementation feasibility index G of the artificially assisted filling process obtained in the step S12, selecting one of a natural micro-saturation filling process, an artificially assisted extrusion supersaturation filling process or an artificially assisted fracturing strong saturation filling process for filling.

Inventors

  • Changyin DONG
  • Wei Liu
  • Honggang Liu
  • Qiang Song
  • Huaiwen Li
  • Haoyu Wang
  • Haobin BAI
  • Guolong Li
  • Chao Wang
  • Tao Sun

Assignees

  • CHINA UNIVERSITY OF PETROLEUM (EAST CHINA)
  • TIANJIN DAGANG DRILLING TECHNOLOGY CO., LTD.

Dates

Publication Date
20260512
Application Date
20250907
Priority Date
20240524

Claims (8)

  1. 1 . A method of artificially assisted filling for sand control and water control of a fractured reservoir, comprising the steps: S11, calculating a fracture productivity evaluation index of the fractured reservoir: F = w 1 · w f w f ⁢ 0 + w 2 · L f L f ⁢ 0 + w 3 · β f 9 ⁢ 0 + w 4 · γ f + w 5 · ρ f ρ f ⁢ 0 ; ( I ) in formula (I), F is the fracture productivity evaluation index, dimensionless; w f is a characteristic slit width of a fracture, mm; w f0 is a characteristic contrast proppant particle size, mm; L f is a characteristic length of a fracture, mm; L f0 is a characteristic contrast slit length, mm; β f is a fracture dip angle, degree; γ f is a fracture flatness, dimensionless; ρ f is a fracture density, fractures/m 3 ; ρ f0 is a characteristic contrast fracture density, fractures/m 3 ; w 1 , w 2 , w 3 , w 4 , w 5 are weight coefficients, taking values of 0.25, 0.25, 0.15, 0.15, 0.2, respectively, dimensionless; S12, calculating an implementation feasibility index of an artificially assisted filling process: G = w 6 · s b - s f s b + w 7 · P f ⁢ 0 - P f P f ⁢ 0 + w 8 · w f w f ⁢ 0 ; ( II ) in formula (II), G is the implementation feasibility index of the artificially assisted filling process, dimensionless; S b is a reservoir matrix strength, MPa; S f is a cementitious strength of a proppant, MPa; P f0 is a reservoir large fracture rupture pressure, MPa; P f is a reservoir natural fracture opening pressure, MPa; w 6 , w 7 , w 8 are weight coefficients, taking values of 0.25, 0.25, 0.5, respectively; S13, selecting and performing one process in technologies of artificially assisted filling for sand control and water control of the fractured reservoir for filling based on the fracture productivity evaluation index F obtained in step S11 and the implementation feasibility index G of the artificially assisted filling process obtained in step S12, wherein: when F>0.75 and G>0.35, a natural micro-saturation filling process is selected for filling; when F>0.75 and G≤0.35, an artificially assisted extrusion supersaturation filling process is selected for filling; when 0.75≥F>0.5 and G>0.5, an artificially assisted extrusion supersaturation filling process is selected for filling; when 0.75≥F>0.5 and G≤0.5, an artificially assisted fracturing strong saturation filling process is selected for filling; when 0.5≥F>0.25 and G>0.75, an artificially assisted extrusion supersaturation filling process is selected for filling; when 0.5≥F>0.25 and G≤0.75, an artificially assisted fracturing strong saturation filling process is selected for filling; when 0.25≥F>0.05, an artificially assisted fracturing strong saturation filling process is selected for filling; and when F≤0.05, no filling is performed or an artificially assisted fracturing strong saturation filling process is selected for filling; wherein: filling technology parameters of the natural micro-saturation filling process comprise d a0 >0.12 mm and construction parameters of the natural micro-saturation filling process comprise: 0 MPa<Pw−Pc<1 MPa, a sand ratio Rs of 80-120%, and a displacement Q of 1-1.5 m 3 /min; filling technical parameters of the artificially assisted extrusion supersaturation filling process comprise 0.045 mm<d a0 <0.12 mm and construction parameters of the artificially assisted extrusion supersaturation filling process are: 1<Pw−Pc<2 MPa, a sand ratio Rs of 60-140%, and a displacement Q of 1.5-2.5 m 3 /min; and filling technology parameters of the artificially assisted fracturing strong saturation filling process comprise 0 mm<d a0 <0.045 mm and construction parameters of the artificially assisted fracturing strong saturation filling process are: 2<Pw−Pc<4 MPa, a sand ratio Rs of 40-160%, and a displacement Q of 2-4 m 3 /min; wherein d a0 is a filling particle size, Pw is a well bottom pump pressure, Pc is a fracture closure stress, Rs is a sand ratio, and Q is a displacement; wherein the performing in step S13 comprises the following steps: S131, opening a casing gate, and washing a well with a washing fluid circularly, wherein a well bottom pump pressure used for washing the well is Pta, and a displacement is Qa; S132, closing the casing gate, and extruding solid phase particles with a filling particle size dao into a natural fracture, where a well bottom pump pressure used for extruding is Pw, a displacement is Q, and a sand ratio is Rs; and S133, opening the casing gate, and changing to perform wellbore circulating filling with solid phase particles having a particle size greater than dao, wherein a well bottom pump pressure for wellbore circulating filling is Pw, and a displacement is Q; the natural micro-saturation filling process, the artificially assisted extrusion supersaturation filling process, and the artificially assisted fracturing strong saturation filling process differ in particle size d a0 , well bottom pump pressure Pw, displacement Q, and sand ratio Rs.
  2. 2 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein a calculation method for the w f is: w f = 0 . 5 ⁢ ( w f ⁢ a + w f ⁢ max ) ; and ( III ) in formula (III), w fa is an average slit width of a fracture, mm, and w fmax is a maximum slit width of a fracture, mm.
  3. 3 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein a calculation method for the L f is: L f = 0 . 5 ⁢ ( L f ⁢ a + L f ⁢ max ) ; ( IV ) in formula (IV), L fa is an average length of a fracture, mm; and L fmax is a maximum length of a fracture, mm.
  4. 4 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein the w f0 is an average particle size of a proppant fillable product to be filled.
  5. 5 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein the L f0 takes a value of 5*10 4 mm, or is an average length of a fracture to be filled; and the ρ f0 takes a value of 10 fractures/m 3 .
  6. 6 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein filling technology parameters of the natural micro-saturation filling process, further comprise: an expected filling radial depth of 10-15 m, an expected filling strength of 0.02-0.25 m 3 /m, and an expected filling capacity of 12-20 m 3 ; filling technical parameters of the artificially assisted extrusion supersaturation filling process, further comprise: an expected filling radial depth of 10-30 m, an expected filling strength of 0.05-0.3 m 3 /m, and an expected filling capacity of 10-15, m 3 ; and filling technology parameters of the artificially assisted fracturing strong saturation filling process, further comprise: an expected filling radial depth of 20-40 m, an expected filling strength of 0.2-0.5 m 3 /m, and an expected filling capacity of 8-15 m 3 .
  7. 7 . The method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , wherein step S11 further comprises: performing fracture productivity determination based on the productivity evaluation index F obtained by calculation: if F>0.75, the fracture productivity is rated as “ultra-high abundance fracture development”; if 0.75≥F>0.5, the fracture productivity is rated as “high abundance fracture development”; if 0.5≥F>0.25, the fracture productivity is rated as “medium abundance fracture development”; if 0.25≥F>0.05, the fracture productivity is rated as “weak fracture development”; and if F≤0.05, the fracture productivity is rated as “no fracture development”.
  8. 8 . A method for evaluating a filling effect of a fractured reservoir filling using the method of artificially assisted filling for sand control and water control of the fractured reservoir according to claim 1 , comprising the steps: S21, calculating a post-construction fracture filling ratio, a production fluid moisture content, a daily average oil production, an oil well water breakthrough time, and an output fluid sand content, α = V c V s ; ( V ) in formula (V), α is a fracture filling ratio, dimensionless; V c is an amount of gravels pumped into a fracture during construction, m 3 ; V s is a calculated total volume of a fracture, m 3 ; V c = V a - V b ; ( VI ) in formula (VI), V a is a total amount of gravels pumped into a formation during construction, m 3 ; V b is a horizontal well wellbore annulus volume, m 3 ; β = 1 - n ⁢ R a ∑ i n ⁢ R b ⁢ i ; ( VII ) in formula (VII), β is a production fluid moisture content, dimensionless; n is a number of non-construction wells, dimensionless; R a is an output fluid moisture content of construction wells, dimensionless; R bi is an output fluid moisture content of an ith non-construction well, i=1, 2, 3 . . . n; γ = ∑ i n ⁢ Q bi nQ a ; ( VIII ) in formula (VIII), γ is a daily average oil production, dimensionless; Q a is a daily oil production of a construction well, tons; Q bi is a daily oil production of an ith non-construction well, tons; ζ = 1 - ∑ i n ⁢ T b ⁢ i n ⁢ T a ; ( IX ) in formula (IX), ζ is an oil well water breakthrough time, dimensionless; T bi is a water breakthrough time of an ith non-construction well, days; T a is a water breakthrough time of a construction well, days; η = n ⁢ η a ∑ i n ⁢ η b ⁢ i ; ( X ) in formula (X), η is an output fluid sand content, dimensionless; η bi is an average sand content of fluid output by an ith non-construction well, dimensionless; η a is a sand content of fluid output by a construction well, dimensionless; S22, calculating a comprehensive evaluation index for sand control and water control: N = a ⁢ α + b ⁢ β + c ⁢ γ + d ⁢ ζ + f ⁢ η ; ( XI ) in formula (XI), N is a comprehensive evaluation index for sand control and water control, dimensionless; a, b, c, d, f are weight coefficients, taking values of 0.4, 0.2, 0.15, 0.15, 0.1, respectively; and S23, evaluating the filling effect of the fractured reservoir based on the comprehensive evaluation index N for sand control and water control obtained in step S22: when 0.2≥N>0, it is loose filling with a poor filling effect; when 0.5≥N>0.2, it is generally dense filling with a general filling effect; when 0.7≥N>0.5, it is dense filling with a good filling effect; and when 1.0≥N>0.7, it is highly dense filling with an excellent filling effect.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The application claims priority to Chinese patent application No. 202410654176.2, filed on May 24, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present invention belongs to the technical field of oil and gas engineering, and particularly relates to a method of artificially assisted filling for sand control and water control of a fractured reservoir and a method for evaluating a filling effect. BACKGROUND Fractured oil and gas reservoirs, such as deep fractured carbonate rock oil and gas reservoirs and fractured dense sandstone gas reservoirs in the Tarim Basin in China, have large reserve volumes, and are main target reservoirs for current and future deep oil and gas development. As shown in FIG. 1, there are natural fractures 2 which are different in width, angle and length, are interconnected or are not interconnected in a fractured reservoir 1. Natural fractures 2 are main oil and gas reservoir spaces and permeable channels. Oil and gas reservoirs having natural fracture development are prone to having sand production phenomena during exploitation, i.e., filling in the fractures undergoes slippage crushing under the action of ground stress and production pressure differentials, and formed reservoir produced sand particles 4 are discharged from a wellbore 3 with a fluid, a direction of an arrow in FIG. 1 is a direction of discharging the reservoir produced sand particles 4; and meanwhile, if the reservoir has edge and bottom water 5 that is relatively close in distance, inrush of the edge and bottom water 5 along fractures with larger widths and better liquidity is easy to occur, resulting in early water breakthrough. The problem of sand and water production is one of the key issues limiting the efficient development of fractured oil and gas reservoirs, and efficient sand control and water control are significant technical needs for efficient exploitation of such oil and gas reservoirs. A patent document with Publication No. CN106372377A discloses a fine silt oil layer filling and sand control method, a sand control measure layer and a construction limit pressure are scientifically set according to self-characteristics of a fine silt oil layer, and a recoverable property of a barrier rock by elastic deformation is used for reducing an extent of a fracture extending to a water layer after extrusion and filling, thereby ensuring the sand control effectiveness, and extending the sand control life. The filling method of this patent document is suitable for hydrophobic sandstone sand production wells, and a loss mechanism, a filling mechanism and a filling pattern of natural fractures in fractured reservoirs are much different from those of hydrophobic sandstone sand production wells, so that the filling method disclosed in this patent is not suitable for the fractured reservoirs. Key issues yet to exist with current sand control and water control process technologies for fractured carbonate rock and sandstone reservoirs include: (1) Completion manners of the fractured carbonate rock and sandstone reservoirs are currently dominated by open hole completion, have no sand control function, and easily cause well wall destabilizing collapse and silt production during production, and the wellbore is buried by sand, causing a severe effect on normal production, and increasing maintenance operation costs. Attempts have begun in recent years to run perforated pipes, slotted pipes or other sand control screens into wellbores for sand control and collapse control completion, but the effects are difficult to meet production requirements. (2) The water control technologies for fractured reservoirs are at its beginning, and a small number of tentatively applied water control technologies mainly follow a conventional inflow control device (ICD) for controlling water by screens, which can only achieve regulation of oil and water flow in the wellbores, with a limited scope and effectiveness. (3) At current, sand control and water control cannot be combined for sand production and water production issues for fractured reservoirs, most of them are achieved inside the wellbores by tubular columns, and it is difficult to drill down inside the reservoirs; and the lack of a sand control and water control integration technology for fractured oil and gas reservoirs severely limits the sand control and water control effect of fractured oil and gas reservoirs. SUMMARY In order to solve the drawbacks in the prior art, the present invention discloses a method of artificially assisted filling for sand control and water control of a fractured reservoir and a method for evaluating a filling effect, which adopt the following technical solutions: To facilitate the understanding of the technical solutions of the present invention, a principle of the filling method according to the present invention will first be described with reference to FIG. 2, the princi