Well selection method for water plugging of high-water-content oil wellTechnical Field
The invention belongs to the technical field of oil extraction processes, and particularly relates to a well selection method for water plugging of a high-water-content oil well.
Background
In the process of water injection development of an oil field, the water content of an oil well can continuously rise along with time. Due to the existence of reservoir heterogeneity and cracks, the uneven propulsion of injected water is easy to form a dominant water flow channel or suddenly advance along the cracks, which is easy to cause the accelerated rise of the water content of the oil well and even water logging. The water plugging technology of the oil well is an important means for treating the oil well with high water content (the water content is more than or equal to 60 percent) and keeping the yield stable.
In the implementation process of water shutoff of the oil well, scientific well selection is a foundation and is also an important technical link for implementation of water shutoff of the oil well. At present, the technical means of well selection and loop section for water plugging of an oil well is single, and the parameter of the water content of the oil well is used for carrying out intuitive decision on the basis of the production dynamics of a water injection well and the oil well. The higher the water content of the oil well, the more water plugging needs to be implemented. The water content reflects the water control urgency degree of the production face in the current stage of the oil well to a certain extent, reflects the development degree of a dominant water flow channel in the oil layer water injection development process, and has certain adaptability by being used as a water plugging and well selecting basis and water plugging priority judgment. However, the water content used as a decision for selecting a water plugging well has two disadvantages, one is that the water content can only reflect the current condition of the oil well and cannot reflect the dynamic change condition of the oil well along with time since the production is put into operation; and secondly, when the water content of the oil well is the same, the priority level of water plugging is difficult to be quickly judged.
In fact, the change of the water content along with time in the production process of the oil well is complex, the water content is increased, decreased and fluctuated in different periods, and the change amplitude is different.
Disclosure of Invention
The invention aims to provide a well selection method for water plugging of a high-water-content oil well, so as to solve the problems.
In order to achieve the purpose, the invention adopts the following technical scheme:
a well selection method for water plugging of a high water content oil well comprises the following steps:
step 1, the total number of oil wells produced in a target block is M, and water plugging is carried out on N oil wells when T and T are greater than 0 and N is less than M; recording data sequences of water contents and corresponding time of all M oil wells within 0-T production time;
step 2, respectively drawing curves of the M oil well data sequences recorded in the step 1 by taking time as an abscissa and taking water content as an ordinate;
step 3, recording a relation function of the water content and the time as f ═ f (t) according to the curve drawn in the step 2, and recording t as the production time; respectively calculating the water content rising index F of the oil wells with M portswcA value;
step 4, raising the water content index F of the oil well with M portswcAnd sequencing the values from large to small, and sequentially selecting the corresponding N oil wells, namely the wells for preferably plugging water.
Further, the unit of time T in step 1 is day, month or year.
Further, step 3 water content rising indexWherein,the water content of the oil well is expressed from f within the production time of 0 to T0Rises to fTIs integrated.
Go toOf step (f)0Water content at 0 time, fTAnd the water content of the oil well at the time T is corresponding to the water content of the oil well.
Further, the water content increase index F in the step 3wcThe significance of is that: fwcThe larger the value is, the higher the water content and the flooding degree of the oil well are, the more developed an oil layer water drive dominant channel controlled by the oil well is, and the higher the water plugging priority is; conversely, the lower the water shutoff priority.
Compared with the prior art, the invention has the following technical effects:
according to the method, the area integral is carried out on the relation function of the water content changing along with the time by utilizing the related data of the water content and the time in the production process of the oil well, the corresponding mathematical calculation is carried out, and finally the water content rising index of the oil well is obtained.
Drawings
FIG. 1 is a schematic representation of the water cut of an oil well as the time of production;
FIG. 2W 24-09 well water cut curve;
FIG. 3W 24-07 well water cut curve;
FIG. 4W 20-115 well water cut curve;
FIG. 5X 78-30 well water cut curve;
FIG. 6X 75-30 well water cut curve;
FIG. 7X 74-43 well water cut curve;
FIG. 8X 65-12 well water cut curves.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
referring to fig. 1 to 8, a method for selecting a high water content oil well for water plugging includes the following steps:
step 1, the total number of oil wells produced in a target block is M, and water plugging is carried out on N oil wells when T and T are greater than 0 and N is less than M; recording data sequences of water contents and corresponding time of all M oil wells within 0-T production time;
step 2, respectively drawing curves of the M oil well data sequences recorded in the step 1 by taking time as an abscissa and taking water content as an ordinate;
step 3, recording a relation function of the water content and the time as f ═ f (t) according to the curve drawn in the step 2, and recording t as the production time; respectively calculating the water content rising index F of the oil wells with M portswcA value;
step 4, raising the water content index F of the oil well with M portswcAnd sequencing the values from large to small, and sequentially selecting the corresponding N oil wells, namely the wells for preferably plugging water.
The unit of the time T in the step 1 is day, month or year.
Step 3 Water content rising indexWherein,the water content of the oil well is expressed from f within the production time of 0 to T0Rises to fTIs integrated.
f0Water content at 0 time, fTAnd the water content of the oil well at the time T is corresponding to the water content of the oil well.
Water content increase index F of step 3wcThe significance of is that: fwcThe larger the value is, the higher the water content and the flooding degree of the oil well are, the more developed an oil layer water drive dominant channel controlled by the oil well is, and the higher the water plugging priority is; conversely, the lower the water shutoff priority.
FIG. 1 is a plot of water cut f (T) of a well versus production time T, where the X-axis is time and the Y-axis is water cut. Corresponding water content is from f within 0-T0Rises to fT. For illustration, the following auxiliary lines are required: the crossing time point T is a point a intersected by a straight line (a dotted line) parallel to the Y axis and the water content curve and connected with afT. Is passing through f0The point is taken as a straight line (dotted line) perpendicular to the Y-axis and compared to the straight line aT to the point b.
The water content is from f within 0 to T0Rises to fTIs integrated to obtainThe mathematical meaning is expressed as 0f in FIG. 10area enclosed by aT. Calculating f0The value of T is 0f in FIG. 10bT, the rectangular area enclosed by the bT. ThenI.e. the area of the shaded portion in fig. 1.
Symbol F for water content ratio rising indexwcAnd then:
Fwcthe mathematical meaning of (a) is expressed as the ratio of the shaded area in figure 1 to the time of the production cycle T. During time T, FwcThe larger the value is, the higher the water content and the flooding degree of the oil well are, the more developed an oil layer water drive dominant channel controlled by the oil well is, and the higher the water plugging priority is; conversely, the lower the water shutoff priority. According to the big to small pairs FwcAnd sequencing the values, and sequentially corresponding the oil wells which need to be blocked.
Example 1:
in block 3 high water content oil wells, 2 wells were selected as water shutoff implementing wells. And (5) carrying out specific example well selection on the water plugging of the 3 oil wells in the block.
1) The initial water content of the target well w24-09 is 27%, and the water content is 85% after 7 years of production; the initial water content of the target well w24-07 is 32%, and the water content is 84% after 7 years of production; the initial water content of the target well w20-115 is 62%, and the water content after 7 years of production is 85%. The water content data sequence corresponding to the three oil wells is shown in the following table 1.
TABLE 1
2) And (3) drawing a curve by taking the production time as an abscissa and the water content as an ordinate according to the data sequence recorded in the step 1) in the table 1. The w24-09 well corresponds to FIG. 2, the w24-07 well corresponds to FIG. 3, and the w20-115 well corresponds to FIG. 4.
3) Calculating the water content rising index F according to the curve chart drawn in the step 2)wcThe value is obtained. The ratio of the shaded area to the production time in FIGS. 2, 3 and 4 is the water content increase indexWherein,the initial water content is f to 7 years0Rises to fTIs the integral of the change curve of (a), which is the shaded area in fig. 2, fig. 3 and fig. 4, respectively; f. of0The T value is the rectangular area in the lower portion of the hatching in fig. 2, 3, and 4, respectively. Finally obtaining the F of the w24-09 wellwc0.404, w24-07 wellsFwcF for 0.247, w20-115 wellwcIs 0.101.
4) When the water content is equivalent after 7 years of production (85% for w24-09 well, 84% for w24-07 well and 85% for w20-115 well), F of three wellswcThe values are w24-09, w24-07 and w20-115 from large to small. According to FwcThe meaning of the characterization shows that the higher the water content and the water flooding degree of the w24-09 well and the w24-07 well, the more developed the oil layer water drive dominant channel controlled by the oil well, and the higher the water plugging priority. Therefore, the w24-09 well and the w24-07 well are preferably selected to carry out water plugging.
Example 2
In block 2 high water cut oil wells, 1 well was selected as the water shutoff implementation well. And (5) carrying out specific example well selection on the water plugging of the 2 oil wells in the block.
1) The initial water content of the target well x78-30 is 15%, and the water content is 94% after 18 months of production; the initial water content of the target well x75-30 is 18%, and the water content after 18 months of production is 96%. The water cut data sequence for both wells is shown in table 2 below.
TABLE 2
2) And (3) drawing a curve by taking the production time as an abscissa and the water content as an ordinate according to the data sequence recorded in the step 1) in the table 2. The x78-30 wells correspond to FIG. 5 and the x75-30 wells correspond to FIG. 6.
3) Calculating the water content rising index F according to the curve chart drawn in the step 2)wcThe value is obtained. The ratio of the shaded area to the production time in FIGS. 5 and 6 is the water content increase indexWherein,the initial water content is f within 0-18 months0Rises to fTIs the integral of the change curve of (a), which is the shaded area in fig. 5 and 6, respectively; f. of0The T value is the rectangular area shaded in fig. 5 and 6, respectively. Finally obtaining F of x78-30 wellwcF for 0.442, x75-30 wellswcIs 0.370.
4) When the water content is equivalent after 18 months of production (94% for x78-30 wells and 96% for x75-30 wells), F of the two wells is calculatedwcThe values are ordered sequentially from large to small. F for x78-30 wellwcLarge value, x75-30 well FwcThe value is small. According to FwcThe meaning of the characterization indicates that the water content and the water flooding degree of the x78-30 well are high, the water drive dominant channel of an oil layer controlled by the oil well develops, and the water plugging priority is high. Therefore, the x78-30 wells are preferably selected for water plugging.
Example 3:
in block 2 high water cut oil wells, 1 well was selected as the water shutoff implementation well. And (5) carrying out specific example well selection on the water plugging of the 2 oil wells in the block.
1) The initial water content of the target well x74-43 is 19%, and the water content is 94% after 5 years of production; the initial water content of the target well x65-12 is 17%, and the water content after 9 years of production is 92%. The water cut data sequence for the two wells is shown in table 3 below.
TABLE 3
2) The data sequence recorded in the step 1) in the table 3 is plotted by taking the production time as an abscissa and the water content as an ordinate. The x74-43 wells correspond to FIG. 7, and the x65-12 wells correspond to FIG. 8.
3) Calculating the water content rising index F according to the curve chart drawn in the step 2)wcThe value is obtained. The ratio of the shaded area to the production time in FIGS. 7 and 8 is the water content increase indexWherein,the initial water content is f to 5 years and 0 to 9 years0Rises to fTIs the integral of the change curve of (a), which is the shaded area in fig. 7 and fig. 8, respectively; f. of0The T value is the rectangular area in the lower portion of the hatching in fig. 7 and 8, respectively. Finally obtaining F of x74-43 wellwcF for 0.547, x65-12 wellwcIs 0.608.
4) When the water content of the x74-43 well is equivalent to that of the x65-12 well after 5 years of production (94% for the x74-43 well and 92% for the x65-12 well), F of the two wells is calculatedwcThe values are ordered sequentially from large to small. F for x65-12 wellwcLarge value, x74-43 well FwcThe value is small. According to FwcThe meaning of the characterization indicates that the water content and the water flooding degree of the x65-12 well are high, the water drive dominant channel of an oil layer controlled by the oil well develops, and the water plugging priority is high. Therefore, the x65-12 well is preferably selected to implement water shutoff.
The water content rising index calculation method provided by the invention has the advantages that the data required by calculation is convenient to record, the calculation is simple, the operation is strong, the operation is easy, compared with the traditional water content method, the water drive condition of the oil layer and the dynamic change rule of the water content are more accurately reflected by the method, and the method has the characteristics of rapidness, simplicity, convenience and strong practicability when being used for the decision of water plugging and well selection of the oil well.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention.