Method for nitrogen foam oil displacement and yield increase of oil well

Abstract

The invention provides a nitrogen foam oil displacement and yield increase method for an oil well, which comprises the following steps: firstly, calculating the volume of nitrogen foam liquid according to a formula, then calculating the underground volumes of nitrogen and foam liquid according to the volume of the nitrogen foam liquid, and then calculating the mass of a foaming agent according to the volume of the foam liquid; the underground nitrogen volume is calculated according to the nitrogen foam liquid volume and the foam liquid volume, and the ground nitrogen volume is calculated according to the underground nitrogen volume; according to the method for calculating the volume of nitrogen foam liquid of the vertical well # imgabs0 # and the volume of nitrogen foam liquid of the horizontal well # imgabs1 #, the actual required injection amount of the ground can be directly obtained according to geological characteristic data provided by an oil well in a common data unit format in combination with the single well construction design injection amount, the problems of unit conversion, repeated calculation and the like in the calculation process are reduced, and the calculation efficiency is improved. Therefore, the calculation efficiency of data analysis is improved, and oil well yield increase is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil well exploitation methods, and in particular relates to a method for increasing oil production through nitrogen foam flooding in oil wells, data calculation of nitrogen foam flooding schemes for vertical wells and horizontal wells, and advanced calculation principles and new calculation methods. Background Art

[0002] At present, oil well nitrogen foam flooding and production increase have been widely used in carbonate reservoirs and heavy oil reservoirs at home and abroad, and have achieved certain results. In the construction of nitrogen foam flooding and production increase, it is often necessary to invest a lot of time in data analysis and calculation to calculate the injection pressure range of the work area, the actual nitrogen foam injection volume and other data. The work area generally contains multiple wells. During the data analysis and calculation process, the different data of a single well causes the calculation parameters to change. The data unit during calculation must also be unified with the data unit in the formula, which requires the data calculation process to be changed accordingly, making the calculation process cumbersome, increasing the calculation time and reducing the calculation efficiency.

[0003] How to further optimize the nitrogen foam flooding method of oil wells to further increase oil well production is a technical problem that technicians in this field urgently need to solve. Summary of the invention

[0004] The purpose of the present invention is to provide a method for increasing oil production by nitrogen foam flooding in oil wells.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for increasing oil production by nitrogen foam flooding in an oil well, firstly according to the actual reservoir and single well parameters of a single well, combined with empirical coefficients, a specific calculation formula is selected according to the well type, and the volume of nitrogen foam liquid is calculated;

[0007] Then according to the gas-liquid ratio of nitrogen to foam liquid Calculate the underground volumes of nitrogen and foam liquid;

[0008] Then, since the volume of the foam liquid does not change during the injection process, the underground volume of the foam liquid = the surface volume of the foam liquid;

[0009] Then, the mass of the foaming agent is calculated based on the density and concentration of the foam liquid;

[0010] Then, since the nitrogen is compressed during the injection process, the underground volume of nitrogen is different from the surface volume. The surface volume of nitrogen is calculated based on the underground volume of nitrogen.

[0011] Preferably, including:

[0012] The calculation formula for the volume of nitrogen foam liquid in vertical wells is: Q Sis the designed volume of nitrogen foam fluid in vertical well, m 3 ;

[0013] n is the design injection coefficient;

[0014] R is the sweep radius, m;

[0015] h is the oil layer thickness, m;

[0016] is the reservoir porosity, %;

[0017] E S is the area sweep coefficient;

[0018] E V is the longitudinal sweep coefficient;

[0019] The calculation formula for the volume of nitrogen foam fluid in horizontal wells is: Q H is the designed volume of nitrogen foam fluid in the horizontal well, m 3 ;

[0020] n is the design injection coefficient;

[0021] R is the sweep radius, m;

[0022] H is the length of the horizontal section, m;

[0023] h is the oil layer thickness, m;

[0024] is the reservoir porosity, %;

[0025] E S is the area sweep coefficient;

[0026] E V is the longitudinal sweep coefficient.

[0027] Preferably, it also includes:

[0028] The calculation formula for the foam liquid volume of a vertical well is:

[0029]

[0030] The calculation formula of the foam fluid volume of horizontal wells is:

[0031]

[0032] V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ;

[0033] GLR is the gas-liquid ratio.

[0034] Preferably, it also includes:

[0035] The calculation formula of the foaming agent quality of vertical well is:

[0036] The calculation formula of the foaming agent quality of horizontal wells is:

[0037] m S is the mass of the vertical well frother, t;

[0038] m H is the mass of the horizontal well foaming agent, t;

[0039] ρ is the density of foam liquid, kg / m 3 ;

[0040] V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ;

[0041] N is the foam liquid concentration, wt%.

[0042] Preferably, it also includes:

[0043] The calculation formula for the underground volume of nitrogen in a vertical well is:

[0044] The calculation formula for the underground volume of nitrogen in a horizontal well is:

[0045] V SG1 is the underground volume of nitrogen in vertical wells, m 3 V HG1 is the underground volume of nitrogen in horizontal wells, m 3 .

[0046] Preferably, it also includes:

[0047] The calculation formula for the nitrogen surface volume of a vertical well is:

[0048]

[0049] The calculation formula for the aboveground volume of nitrogen in a horizontal well is:

[0050]

[0051] V SG2 is the surface volume of nitrogen in vertical wells, m 3 ;

[0052] V HG2 is the surface volume of nitrogen in the horizontal well, m3 ;

[0053] P1 is the formation pressure, MPa;

[0054] P2 is the ground pressure, MPa;

[0055] T1 is the formation temperature, K;

[0056] T2 is the ground temperature, K;

[0057] t1 is the formation temperature, °C;

[0058] t2 is the ground temperature, ℃.

[0059] Compared with the prior art, the present invention has the following advantages and technical effects:

[0060] This calculation method can directly obtain the actual required injection volume on the ground based on the geological characteristic data provided by the oil well in a commonly used data unit format combined with the single well construction design injection volume, thereby reducing problems such as unit conversion and repetitive calculations in the calculation process, reducing the tedious steps in the calculation process, and thus improving the calculation efficiency of data analysis.

[0061] The data required for this application include the oil layer and surface data of the work area, the designed gas-liquid ratio of nitrogen foam liquid in a single well and the concentration of foam liquid;

[0062] Enter the oil layer and ground data provided by the work area, the designed gas-liquid ratio of the single-well nitrogen foam liquid and the foam liquid concentration into the required positions, convert the data units using the temperature conversion formula, select different formulas to calculate the volume of the nitrogen foam liquid according to the well type of the injection well, and then use the designed gas-liquid ratio of the single-well nitrogen foam liquid to calculate the underground volume of the nitrogen and foam liquid to be injected, use the ideal gas state equation formula to calculate the ground volume of the nitrogen to be injected, and use the mass formula to calculate the mass of the foam liquid, and then use the foam liquid solution concentration to calculate the mass of the required foaming agent.

[0063] In this application, heavy oil wells are injected with steam for thermal recovery. After multiple rounds of injection, steam channeling is easily caused by the top overlap and the advance of high permeability layers, resulting in poor thermal recovery effects. Before or during steam injection, nitrogen (foam) is pre-placed or injected, so that the single steam development method is changed to a composite method of steam, nitrogen and chemicals, improving the thermal recovery effect of heavy oil wells. Foam has the characteristics of "blocking large but not small, blocking water but not oil". Nitrogen foam continuously bursts and regenerates in porous media, dynamically blocks high water-content pores during oil-water flow, expands the affected range, and foam preferentially enters the large pores formed by water channeling, balancing the advancement speed of the water drive front. The foam liquid has high viscosity and a small difference in mobility with crude oil, avoiding unidirectional and interlayer advances. After the foam bursts, the escaping gas overlaps the top of the reservoir and displaces the remaining oil that is difficult to reach with water drive; the foaming agent is a surfactant, which greatly improves the efficiency of oil washing and realizes water control and oil increase in oil wells. After being compressed, nitrogen is injected into the formation to quickly replenish formation energy, increase the displacement pressure difference of underground fluids, overlay the top of the reservoir, and replace the remaining oil in the high parts of the reservoir. The gas molecules have a small diameter and displace the remaining oil in micro-cracks and micro-pore throats, thereby increasing oil well production.

[0064] Compared with the common problems in traditional design methods, such as low efficiency, high error rate, high data reuse rate, and chaotic data management, this method can accurately simulate and customize the reservoir under study, combine the characteristic parameters of the reservoir, construct a design process that fits the actual reservoir conditions, and make real-time adjustments based on the actual parameters of the injection well. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 A calculation flow chart of a method for increasing oil production by nitrogen foam flooding in an oil well provided in this application. DETAILED DESCRIPTION

[0066] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of them. Therefore, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] The present application provides a method for increasing oil production by nitrogen foam flooding in oil wells, firstly according to the actual reservoir and single well parameters of a single well, combined with empirical coefficients, a specific calculation formula is selected according to the well type, and the volume of nitrogen foam liquid is calculated;

[0068] Then according to the gas-liquid ratio of nitrogen to foam liquid Calculate the underground volumes of nitrogen and foam liquid;

[0069] Then, since the volume of the foam liquid does not change during the injection process, the underground volume of the foam liquid = the surface volume of the foam liquid;

[0070] Then, the mass of the foaming agent is calculated based on the density and concentration of the foam liquid;

[0071] Then, since the nitrogen is compressed during the injection process, the underground volume of nitrogen is different from the surface volume. The surface volume of nitrogen is calculated based on the underground volume of nitrogen.

[0072] In one embodiment of the present application, it includes:

[0073] The calculation formula for the volume of nitrogen foam liquid in vertical wells is: Q S is the designed volume of nitrogen foam fluid in vertical well, m 3 ;

[0074] n is the design injection coefficient;

[0075] R is the sweep radius, m;

[0076] h is the oil layer thickness, m;

[0077] is the reservoir porosity, %;

[0078] E S is the area sweep coefficient;

[0079] E V is the longitudinal sweep coefficient;

[0080] The calculation formula for the volume of nitrogen foam fluid in horizontal wells is: Q H is the designed volume of nitrogen foam fluid in the horizontal well, m 3 ;

[0081] n is the design injection coefficient;

[0082] R is the sweep radius, m;

[0083] H is the length of the horizontal section, m;

[0084] h is the oil layer thickness, m;

[0085] is the reservoir porosity, %;

[0086] E S is the area sweep coefficient;

[0087] E V is the longitudinal sweep coefficient.

[0088] In one embodiment of the present application, it also includes:

[0089] The calculation formula for the foam liquid volume of a vertical well is:

[0090]

[0091] The calculation formula of the foam fluid volume of horizontal wells is:

[0092]

[0093] V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ;

[0094] GLR is the gas-liquid ratio.

[0095] In one embodiment of the present application, the calculation formula of the foaming agent mass of the vertical well is also included:

[0096] The calculation formula of the foaming agent quality of horizontal wells is:

[0097] m S is the mass of the vertical well frother, t;

[0098] m H is the mass of the horizontal well foaming agent, t;

[0099] ρ is the density of foam liquid, kg / m 3 ;

[0100] V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ;

[0101] N is the foam liquid concentration, wt%.

[0102] In one embodiment of the present application, the calculation formula of the underground volume of nitrogen in a vertical well is also included:

[0103] The calculation formula for the underground volume of nitrogen in a horizontal well is:

[0104] V SG1 is the underground volume of nitrogen in vertical wells, m 3 V HG1 is the underground volume of nitrogen in horizontal wells, m 3 In one embodiment of the present application, the calculation formula for the nitrogen surface volume of a vertical well is also included:

[0105]

[0106] The calculation formula for the aboveground volume of nitrogen in a horizontal well is:

[0107]

[0108] V SG2 is the surface volume of nitrogen in vertical wells, m 3 ;

[0109] V HG2 is the surface volume of nitrogen in the horizontal well, m 3 ;

[0110] P1 is the formation pressure, MPa;

[0111] P2 is the ground pressure, MPa;

[0112] T1 is the formation temperature, K;

[0113] T2 is the ground temperature, K;

[0114] t1 is the formation temperature, °C;

[0115] t2 is the ground temperature, ℃.

[0116] In the present application, the difference between the above-mentioned nitrogen foam liquid volume and the foam liquid volume is: the nitrogen foam liquid volume includes two parts, the volume of nitrogen injected underground and the volume of foam liquid, and the foam liquid volume is a part of the nitrogen foam liquid volume.

[0117] In this application, the gas-liquid ratio is:

[0118] V G is the gas injection volume, m 3 ;

[0119] V L is the injection volume, m 3 .

[0120] The calculation process in this application:

[0121] Q S The calculated volume is the designed underground nitrogen foam liquid volume (for horizontal wells,

[0122]

[0123] According to the gas-liquid ratio of nitrogen and foam liquid Then the underground volumes of nitrogen and foam liquid can be calculated. The underground volume of foam liquid is The volume of nitrogen underground is V G1 =QV L ;

[0124] After obtaining the underground volumes of nitrogen and foam liquid, due to pressure, the volume of foam liquid remains unchanged during the injection process (above ground = below ground), while nitrogen will be compressed during the injection process. Therefore, the underground volume of nitrogen is different from the above ground volume. The underground volume of nitrogen needs to be calculated using the ventilation rate formula To convert the floor volume, since the temperature in the ventilation rate formula must be in Kelvin, the temperature conversion formula is used: T = t + 273.15 to convert Celsius to Kelvin;

[0125] The foam liquid is prepared from the foaming agent solution. The required foaming agent mass m is calculated based on the density and concentration of the foam liquid. S =ρV L N;

[0126] So far, the required quantities of all raw materials under ground conditions are obtained, including the ground volume of nitrogen and the mass of foaming agent.

[0127] The methods and devices not described in detail in the present invention are all prior art and will not be described in detail.

[0128] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0129] Example 1

[0130] The ground temperature in a certain block is 20℃, the ground pressure is 0.1MPa, the formation temperature is 43.3℃, ​​and the formation pressure is 2.1MPa. Nitrogen foam liquid is injected into a vertical well in the block to improve the recovery rate. The production layer of the vertical well is 15m thick, the porosity is 25%, the area sweep coefficient is 0.5, the longitudinal sweep coefficient is 0.4, the estimated sweep radius is 50m, the designed injection nitrogen foam liquid volume ratio GLR is 2:1, and the foam liquid concentration is 1wt%.

[0131] In Example 1, the calculation process of the volume of nitrogen foam liquid is:

[0132]

[0133] Calculation process of foam liquid volume:

[0134]

[0135] Calculation process of foaming agent mass:

[0136]

[0137] Calculation process of nitrogen underground volume:

[0138]

[0139] Calculation process of nitrogen ground volume:

[0140]

[0141] Example 2

[0142] The ground temperature in a certain block is 20℃, the ground pressure is 0.1MPa, the formation temperature is 43.3℃, ​​and the formation pressure is 2.1MPa. Nitrogen foam liquid is injected into a horizontal well in the block to improve the recovery rate. The production layer of the horizontal well is 15m thick, the porosity is 25%, the horizontal section length is 150m, the area sweep coefficient is 0.5, the longitudinal sweep coefficient is 0.4, the expected sweep radius is 50m, the designed injection nitrogen foam liquid volume ratio GLR is 2:1, and the foam liquid concentration is 1wt%.

[0143] In Example 2, the calculation process of the volume of nitrogen foam liquid is:

[0144]

[0145] Calculation process of foam liquid volume:

[0146]

[0147] Calculation process of foaming agent mass:

[0148]

[0149] Calculation process of underground volume of nitrogen;

[0150]

[0151] Calculation process of nitrogen ground volume:

[0152]

[0153] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for increasing oil production by nitrogen foam flooding in an oil well, characterized in that: First, according to the actual reservoir and single well parameters of a single well, combined with empirical coefficients, a specific calculation formula is selected according to the well type to calculate the volume of nitrogen foam liquid; Then according to the gas-liquid ratio of nitrogen to foam liquid Calculate the underground volumes of nitrogen and foam liquid; Then, since the volume of the foam liquid does not change during the injection process, the underground volume of the foam liquid = the surface volume of the foam liquid; Then, the mass of the foaming agent is calculated based on the density and concentration of the foam liquid; Then, since the nitrogen is compressed during the injection process, the underground volume of nitrogen is different from the surface volume. The surface volume of nitrogen is calculated based on the underground volume of nitrogen.

2. The method for increasing oil production by nitrogen foam flooding in an oil well according to claim 1, characterized in that: include: The calculation formula for the volume of nitrogen foam liquid in vertical wells is: Q S is the designed volume of nitrogen foam fluid in vertical well, m 3 ; n is the design injection coefficient; R is the sweep radius, m; h is the oil layer thickness, m; is the reservoir porosity, %; E S is the area sweep coefficient; E V is the longitudinal sweep coefficient; The calculation formula for the volume of nitrogen foam fluid in horizontal wells is: Q H is the designed volume of nitrogen foam fluid in the horizontal well, m 3 ; n is the design injection coefficient; R is the sweep radius, m; H is the length of the horizontal section, m; h is the oil layer thickness, m; is the reservoir porosity, %; E S is the area sweep coefficient; E V is the longitudinal sweep coefficient.

3. A method for increasing oil production by nitrogen foam flooding in an oil well according to claim 2, characterized in that: Also includes: The calculation formula for the foam liquid volume of a vertical well is: The calculation formula of the foam fluid volume of horizontal wells is: V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ; GLR is the gas-liquid ratio.

4. The method for increasing oil production by nitrogen foam flooding in an oil well according to claim 3, characterized in that: Also includes: The calculation formula of the foaming agent quality of vertical well is: The calculation formula of the foaming agent quality of horizontal wells is: m S is the mass of the vertical well frother, t; m H is the mass of the horizontal well foaming agent, t; ρ is the density of foam liquid, kg / m 3 ; V SL is the volume of foam fluid in vertical wells, m 3 ; V HL is the volume of foam fluid in horizontal well, m 3 ; N is the foam liquid concentration, wt%.

5. The method for increasing oil production by nitrogen foam flooding in an oil well according to claim 3, characterized in that: Also includes: The calculation formula for the underground volume of nitrogen in a vertical well is: The calculation formula for the underground volume of nitrogen in a horizontal well is: V SG1 is the underground volume of nitrogen in vertical wells, m 3 V HG1 is the underground volume of nitrogen in horizontal wells, m 3 .

6. The method for increasing oil production by nitrogen foam flooding in an oil well according to claim 5, characterized in that: Also includes: The calculation formula for the nitrogen surface volume of a vertical well is: The calculation formula for the aboveground volume of nitrogen in a horizontal well is: V SG2 is the surface volume of nitrogen in vertical wells, m 3 ; V HG2 is the surface volume of nitrogen in the horizontal well, m 3 ; P1 is the formation pressure, MPa; P2 is the ground pressure, MPa; T1 is the formation temperature, K; T2 is the ground temperature, K; t1 is the formation temperature, °C; t2 is the ground temperature, ℃.

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