Fracturing adjusting method based on pressure reaction of adjacent wells

Abstract

The invention relates to the technical field of shale gas horizontal well reconstruction well fracturing, and discloses a fracturing adjustment method based on adjacent well pressure response, which comprises the following steps: S1, establishing a database real-time transmission system to monitor casing pressure data of a gas well in real time, and designing a standard fracturing construction pumping program according to geological conditions; s2, construction is carried out according to a standard pump injection program, casing pressure data of the gas wells in the influence range are collected regularly, the well casing pressure rising speed and the well casing pressure rising amplitude of the gas wells are calculated, the gas well (adjacent well) with the largest influence is determined, the construction displacement of the fractured well is detected in real time, and the time for collecting the data can be adjusted; and S3, according to the pressure rising speed, the pressure rising amplitude, the construction displacement and the construction stage of the adjacent well, the fracturing pump injection method is adjusted. The casing pressure rising rate and the pressure rising amplitude of the adjacent well in the construction process are monitored, and the fracturing mode is adjusted in combination with the construction progress, so that the negative influence of fracturing impact is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas horizontal well reconstruction well fracturing, and particularly relates to a fracturing adjustment method based on the pressure response of adjacent wells. Background Art

[0002] The platform well group development has become the main mode of efficient shale gas development in China. To improve the reserve utilization rate and recovery rate, multiple shale gas fields adopt the development technical solutions of plane densification and vertical multi-layers, such as Figure 6 As shown, after the gas well is drilled vertically to a certain depth from the ground and then turns, and there are multiple layers of gas wells. While the well spacing is further reduced, the fracturing reconstruction intensity is increased. As the old wells produce, the formation pressure gradually decreases. During the fracturing construction period of the new wells, the well interference phenomenon occurs frequently, and extensive research has been carried out at home and abroad. On the one hand, when the fractures extend excessively during the fracturing of the new well, it will have a negative impact on the surrounding producing wells. After opening the well, the water production increases, and the gas production decreases significantly or even it is difficult to resume production through blowout, and measures such as gas lift are needed to resume production, which takes a long time, increases the cost input, and seriously affects the production efficiency. On the other hand, if the fracturing impact is avoided only by reducing the fracturing reconstruction range and other methods, it may lead to insufficient reconstruction between wells. Therefore, how to avoid the fracturing impact has become an urgent problem to be solved while ensuring the full utilization of the remaining reserves between wells during the fracturing construction. Summary of the Invention

[0003] The present invention aims to provide a fracturing adjustment method based on the pressure response of adjacent wells to avoid the fracturing impact.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A fracturing adjustment method based on the pressure response of adjacent wells, comprising the following steps:

[0005] S1: Establish a database real-time transmission system to monitor the casing pressure data of the gas well in real time, and design a standard fracturing construction pumping program according to the geological conditions;

[0006] S2: Construct according to the standard fracturing construction pumping program, and regularly collect the casing pressure data of the gas wells within the influence range, calculate the casing pressure starting rate and starting amplitude of the gas wells, determine the gas well with the greatest influence, that is, the adjacent well, and detect the construction displacement of the fracturing well in real time. The time for collecting data can be adjusted;

[0007] S3: Adjust the fracturing pumping method according to the starting rate, starting amplitude, construction displacement and construction stage of the adjacent well.

[0008] The beneficial effect of this solution is: According to the actual situation, research is carried out from several aspects such as interference phenomena, mechanisms, on-site diagnosis and intervention measures.

[0009] According to research and practice, for the rapid identification of inter-well interference types, the process of fracturing impact can generally be divided into three stages:

[0010] The first stage is the pressure conduction of the fractured rock matrix, manifested as a slight increase in the casing pressure of the adjacent well, with the pressure rise amplitude < 0.7 MPa and the pressure rise rate being slow, with a slope < 0.001 MPa / min. The stress state change caused by the interference in this stage is conducive to displacing the free gas between wells to the production well, thus being beneficial to increasing the production of adjacent wells and belonging to positive interference.

[0011] The second stage is the mixed response, which is the stress interaction between the new and old well fractures and the local fracture interference caused by the communication between natural fracture intervals. The main feature is that after injecting for a period of time, a gentle pressure increase occurs, with a slope of 0.001 - 0.005 MPa / min, and the pressure slowly rises after the pump is stopped, with the overall pressure rise amplitude < 5 MPa. In practice, the mixed response is mainly positive interference.

[0012] The third stage is the direct fracturing impact, where the hydraulic fractures of the new and old wells directly communicate, the fracturing fluid directly flows into the fractures of the old well, and the casing pressure of the old well increases sharply. The direct fracturing impact response usually has a magnitude > 5 MPa and a main slope > 0.1 MPa / min. Such interference is mainly negative.

[0013] Based on the change rate of the casing pressure of the adjacent well and the change in the pressure rise amplitude, it is convenient, fast, and accurate to judge the impact stage of the new well fracturing on the adjacent well, so as to control the fracturing progress of the new well, ensure the full progress of the inter-well transformation, and on the basis of fully mobilizing the remaining reserves between wells, avoid the negative interference of the fracturing impact on the existing gas wells.

[0014] Furthermore, when the construction reaches the middle and late stages according to the standard fracturing construction pumping program, that is, when 80% of the construction fluid volume is injected, S2: the pressure rise rate < 0.001 Mpa / min and the total pressure rise < 0.7 Mpa; S3: the construction pumping displacement is increased at a speed of 0.25 m 3 / min, and an additional fluid volume of 100 - 200 m 3 .

[0015] Beneficial effects: The pressure rise rate < 0.001 Mpa / min and the total pressure rise < 0.7 Mpa. It can be inferred that the fracturing impact of the construction fracturing on the existing gas wells is in the first stage. The stress state change caused by the interference in this stage is conducive to displacing the free gas between wells to the production well, thus being beneficial to increasing the production of adjacent wells and belonging to positive interference. During construction, the pumping displacement can be appropriately increased to ensure the full progress of the inter-well transformation during construction, fully mobilize the remaining reserves between wells, and increase the production.

[0016] Further, S2: The pressure rising rate is 0.001 - 0.005 Mpa / min, and the pressure rising amplitude is < 3 Mpa; S3: Construct according to the standard fracturing construction pumping program.

[0017] Beneficial effect: With the pressure rising rate of 0.001 - 0.005 Mpa / min and the pressure rising amplitude < 3 Mpa, the fracturing impact of the construction on the existing gas wells is in the second stage at this time, mainly positive interference. At this time, the construction can be carried out according to the original design pumping without adjustment.

[0018] Further, S2: The construction pressure is lower than the safety pressure, that is, lower than the construction limit pressure of 20 Mpa, the pressure rising rate is 0.005 - 0.1 Mpa / min, and the pressure rising amplitude is < 5 Mpa; S3: Add 100 - 150 Kg of 30 / 200 - mesh in - seam temporary plugging agent.

[0019] Beneficial effect: With the pressure rising rate of 0.005 - 0.1 Mpa / min, the pressure rising amplitude < 5 Mpa, and the construction pressure lower than the construction limit pressure of 20 Mpa, the fracturing impact of the construction on the existing gas wells is between the second stage and the third stage at this time. Continuing the pumping construction will probably lead to the direct communication between the hydraulic fractures of the new well and the existing gas wells. At this time, adding 30 / 200 - mesh in - seam temporary plugging agent can reduce the probability of direct communication between the hydraulic fractures of the new and old wells and avoid negative impacts.

[0020] Further, if the pressure rising rate is maintained at 0.005 - 0.1 Mpa / min, then a pumping construction attempt of reducing the displacement is carried out. Observe for 3 - 5 minutes every time the displacement is reduced by 1 m 3 / min. If the pressure rising rate drops to 0.001 - 0.005 Mpa / min, then continue the construction at this displacement.

[0021] Beneficial effect: After adding the plugging agent, the pressure rising rate of the adjacent well still remains at 0.005 - 0.1 Mpa / min, indicating that the rock formation in this well section is relatively fragile. At this time, the pumping displacement should be reduced to avoid the direct communication between the hydraulic fractures of the new well and the existing gas wells.

[0022] Further, S2: The construction pressure is higher than the safety pressure, the pressure rising rate is 0.005 - 0.1 Mpa / min, and the pressure rising amplitude is < 5 Mpa; S3: Add 50 - 100 Kg of 30 / 200 - mesh in - seam temporary plugging agent.

[0023] Beneficial effect: With the pressure rising rate of 0.005 - 0.1 Mpa / min, the pressure rising amplitude < 5 Mpa, and the construction pressure higher than the safety pressure, the hydraulic fractures of the new well and the existing gas wells are about to directly communicate. Adding 50 - 100 Kg of 30 / 200 - mesh in - seam temporary plugging agent can force the mid - and far - end fracture networks to turn, avoiding further extension to the low - pressure adjacent wellbore and resulting in the direct communication between the hydraulic fractures of the new well and the existing gas wells.

[0024] Further, in S2: the pressure rising rate > 0.1 Mpa / min or the pressure rising amplitude > 5 Mpa; in S3: reduce the displacement to 1 - 2 m 3 / min, and add 150 - 200 Kg of 4 / 200 - mesh inter - cluster temporary plugging agent.

[0025] Beneficial effects: When the pressure rising rate > 0.1 Mpa / min or the pressure rising amplitude > 5 Mpa, the hydraulic fractures of the new well are initially communicated with those of the existing gas wells. Adding 150 - 200 Kg of 4 / 200 - mesh inter - cluster temporary plugging agent can make the hydraulic fractures turn from the fracture opening, avoid excessive communication, and while ensuring the transformation volume, increase the complexity of the fracture network.

[0026] Further, in S2, the pressure rising situation of the adjacent well and the construction displacement of the fracturing well rise and fall simultaneously. It is necessary to reduce the scale of the pumping construction. At the same time, for the well sections with similar geological conditions and greater interference possibility in the subsequent construction, temporary plugging should be carried out in advance before fracturing for this section.

[0027] Beneficial effects: In S3, the pressure rising situation of the adjacent well and the displacement of the fracturing well rise and fall simultaneously, indicating that some of the hydraulic fractures of the new well are directly communicated with those of the existing gas wells. At this time, it is necessary to reduce the pumping displacement to avoid the communication between other fractures of the existing gas wells and the hydraulic fractures of the new well, resulting in an increase in the water production and a decrease in the gas production of the existing gas wells. At the same time, providing a case for well sections with similar geological conditions is beneficial to the subsequent construction.

[0028] Further, for the well sections with similar geological conditions and greater interference possibility in the subsequent construction, temporary plugging should be carried out in advance before fracturing for this well section, and the dominant fluid - intake channels should be blocked in advance to avoid the initial fracture communication.

[0029] Beneficial effects: By summarizing the geological conditions prone to fracturing shock, similar situations can be effectively avoided in the subsequent process.

[0030] Further, the way of temporary plugging in advance is to add inter - cluster temporary plugging materials after acidizing.

[0031] Beneficial effects: Adding inter - cluster temporary plugging materials directly after acidizing can block the dominant fluid - intake channels in advance, avoid the initial fracture communication, and is beneficial to the subsequent construction and expanding the scope of well - to - well transformation. Description of the Drawings

[0032] Figure 1 It is a chart of the standard fracturing construction pumping program of the present invention;

[0033] Figure 2 It is a conventional fracturing adjustment method;

[0034] Figure 3 It is the fracturing adjustment method of the present invention;

[0035] Figure 4 Schematic diagram of gas well spacing for Case 1;

[0036] Figure 5 Schematic diagram of gas well spacing for Case 2;

[0037] Figure 6 Schematic diagram of well spacing of existing gas wells. Detailed implementation manners

[0038] Embodiment

[0039] A fracturing adjustment method based on the pressure response of adjacent wells, comprising the following steps:

[0040] First, establish a database real-time transmission system to monitor the casing pressure data of gas wells in real time, and design a standard fracturing construction pumping program as shown in Figure 1 the figure.

[0041] Secondly, conduct construction according to the standard fracturing construction pumping program, and collect and pay attention to the starting pressure rate and starting pressure amplitude of the casing pressure of the gas wells within the construction influence range in real time to determine the gas well (adjacent well) with the greatest influence.

[0042] Finally, adjust the fracturing pumping method according to the starting pressure rate, starting pressure amplitude, construction displacement and construction stage of the adjacent well. The adjustment method is as shown in Figure 3 the figure:

[0043] 1. In the middle and late stage of construction (when 80% of the construction fluid volume is injected), if there is no starting pressure in the adjacent well or the starting pressure rate < 0.001 MPa / min and the starting pressure amplitude < 0.7 MPa, increase the construction displacement by 0.25 m 3 / min, and appropriately add 100 - 200 m 3 of fluid volume under the premise of investment permission to improve the transformation effect;

[0044] 2. During the construction period, when the starting pressure rate is 0.001 - 0.005 MPa / min and the starting pressure amplitude < 3 MPa, conduct construction according to the original design pumping, and pay attention to the starting pressure speed and amplitude in real time;

[0045] 3. During the construction period, when the starting pressure rate is 0.005 - 0.1 MPa / min and the starting pressure amplitude < 5 MPa, if the construction pressure is lower than the construction limit pressure of 20 MPa, preferably add 100 - 150 Kg of 30 / 200 - mesh in - seam temporary plugging agent;

[0046] If the construction pressure is relatively high, add 50 - 100 Kg to force the mid - and far - end fracture networks to turn and avoid further extension to the low - pressure adjacent wellbore;

[0047] 4. When the starting pressure rate > 0.1 MPa / min or the starting pressure amplitude > 5 MPa, the possibility of direct fracturing impact is relatively high. Reduce the displacement to 1 - 2 m 3 / min, add 150 - 200 Kg of 4 / 200 - mesh inter - cluster temporary plugging agent, start to turn from the seam opening to avoid excessive communication (i.e., the newly formed cracks during construction are completely connected to the pre - existing old cracks), ensure the transformation volume while increasing the complexity of the fracture network. Steps 3 and 4 can be used alternately;

[0048] 5. If the pressure control effect of adding the temporary plugging agent is still not obvious, conduct a construction attempt with reduced displacement. Observe for 3 - 5 minutes every time the displacement is reduced by 1 m 3 / min. If the pressure build - up rate decreases, reduce the displacement to this value and continue the construction;

[0049] 6. If the pressure in the adjacent well and the displacement of the fracturing well increase and decrease simultaneously, it is inferred that there is a high possibility of direct communication between the artificial hydraulic fractures, and the construction scale needs to be reduced to minimize the negative impact as much as possible.

[0050] 7. For well sections with similar geological conditions and high interference possibility in subsequent construction, temporarily plug this section in advance before fracturing, that is, add inter - cluster temporary plugging materials after acidizing to block the preferential fluid intake channels in advance and avoid the initial fracture communication.

[0051] Beneficial effects:

[0052] Combined with the actual construction phenomena, the fracture response types of shale gas wells are summarized, different types of adjacent - well response pressure build - up rates are formulated, and refined fracture control is carried out through the pressure build - up rate, and the pumping program is optimized in real - time. Since the end of 2020, a total of 134 vertical - horizontal development adjustment wells and 5 refracturing wells have been implemented using this method, reversing the phenomenon that the proportion of negative impacts on the production of adjacent wells by the fracturing wells under construction increases. The proportion of positive and non - impact well times has increased to 87%, effectively improving the recovery rate of the well group and the reserve utilization rate, providing a favorable reference for the efficient development of domestic shale gas fields.

[0053] The following compares the adjustment methods through two cases, one positive and one negative:

[0054] Case 1 (using this adjustment method for fracturing construction)

[0055] Taking the lower - layer infill well A as an example, the positional relationship between A and the existing gas wells around it is as Figure 4 shown. The elevation difference between B and Well A is 19 - 73 m, and the horizontal distance is 94 - 142 m. During the construction of A, the pressure build - up rate and amplitude of B are the largest. That is, during the construction of A, B is the adjacent well, and the pressure build - up situation of the adjacent well is closely monitored during the fracturing of this well.

[0056] As in Figure 1During the 10th stage construction as shown, the rising speed of the casing pressure in the adjacent well B was 0.028 MPa / min, and the pressure increase amplitude was 0.9 MPa, meeting Case 3. 150 Kg of 30 / 200 mesh in-slot temporary plugging agent was added, and the pressure increase was temporarily controlled after the addition. After adjustment, when the displacement was increased, the pressure in the adjacent well further climbed. The pressure increase speed was 0.123 MPa / min, and the pressure increase amplitude was 3.73 MPa, meeting Case 4. 200 Kg of 4 / 200 mesh inter-cluster temporary plugging agent was added, and the subsequent pressure increase situation was controlled.

[0057] By advancing the temporary plugging timing + increasing the dosage + adding multiple times, the further pressure increase in the adjacent well was effectively controlled, ensuring the construction scale.

[0058] In Figure 1 During the 19th stage construction as shown, the rising speed of the casing pressure in the adjacent well was 0.038 MPa / min, and the pressure increase amplitude was 1.96 MPa, meeting Case 3. 150 Kg of 30 / 200 mesh in-slot temporary plugging agent was added, and the pressure increase situation was controlled after the addition. The construction continued until the designed liquid volume was reached.

[0059] Finally, the test production of Well A was 163,000 cubic meters per day, and the test pressure was 15.4 MPa, which was relatively ideal. After the adjacent well resumed production, the production situation improved.

[0060] Case 2 (without using this adjustment method)

[0061] Taking the refractured Well D as an example, as Figure 5 shown, the elevation difference between Well D and Well E was 52 - 55 m, and the horizontal distance was 113 - 117 m. Before the heavy fracturing, the average daily production in continuous production was 27,200 cubic meters per day, and the casing pressure was 9.24 MPa. After the heavy fracturing and resumption of production, continuous production could not be achieved. The average daily production was 20,200 cubic meters per day, and the casing pressure was 7.42 MPa. During the heavy fracturing of Well D, the pressure increase in the adjacent well was not noticed. During the heavy fracturing of Well D, the construction pump injection was not adjusted in real time according to the design. During the construction, it was fractured according to the adjustment method as Figure 2 shown. The casing pressure of Well D increased highly. During the 8th and 9th stage constructions, the casing pressure of the adjacent Well E rose rapidly, with single-stage increases of 10.7 and 7.9 MPa respectively, and the fastest rising speed was 0.79 MPa / min.

[0062] Statistical data for half a year showed that before being affected, in continuous production, the average daily production of the adjacent Well E was 51,500 cubic meters per day, the casing pressure was 10.64 MPa, and the daily water production was 4.02 cubic meters. After being affected, due to sand production, the well was shut in, and the daily produced water volume during single-day blowout was 10.4 - 12.4 cubic meters. Finally, the heavy fracturing test production was 88,100 cubic meters per day, and the test pressure was 6.93 MPa, with unsatisfactory results. The adjacent Well E was negatively affected, and it was difficult to resume production with reduced production.

[0063] The above are only embodiments of the present invention, and common general technical solutions and / or characteristics in the solutions are not described in detail herein. It should be noted that the technical means for solving problems in the above embodiments of the present invention can be combined to solve multiple technical problems simultaneously. For those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A fracturing adjustment method based on the pressure response of adjacent wells, characterized in that: It includes the following steps: S1: Establish a database real-time transmission system to monitor the casing pressure data of gas wells in real time, and design a standard fracturing construction pumping program according to geological conditions; S2: Construct according to the standard fracturing construction pumping program, and regularly collect the casing pressure data of gas wells within the affected range, calculate the starting pressure rate and starting pressure amplitude of the well casing pressure of the gas wells, determine the gas well with the greatest influence, that is, the adjacent well, and detect the construction displacement of the fracturing well in real time. The time for collecting data can be adjusted; S3: Adjust the fracturing pumping method according to the starting pressure rate, starting pressure amplitude, construction displacement and construction stage of the adjacent well.

2. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: When the construction reaches the middle and late stages according to the standard fracturing pumping program, that is, when 80% of the construction fluid volume is injected, S2: when the pressure rising rate < 0.001 Mpa / min and the total pressure rise < 0.7 Mpa; S3: the construction pumping rate is increased at a speed of 0.25 m 3 / min, and an additional fluid volume of 100 - 200 m 3 .

3. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: S2: The starting pressure rate is 0.001 - 0.005 Mpa / min, and the starting pressure amplitude < 3 Mpa; S3: Construct according to the standard fracturing construction pumping program.

4. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: S2: The construction pressure is lower than the safety pressure, that is, lower than the construction limit pressure of 20 Mpa, the starting pressure rate is 0.005 - 0.1 Mpa / min, and the starting pressure amplitude < 5 Mpa; S3: Add 100 - 150 Kg of 30 / 200 mesh in-seam temporary plugging agent.

5. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 4, characterized in that: If the pressure rising rate is maintained at 0.005 - 0.1 Mpa / min, then the pump injection construction attempts to reduce the displacement. For every 1 m 3 / min reduction, observe for 3 - 5 minutes. If the pressure rising rate drops to 0.001 - 0.005 Mpa / min, continue the construction at this displacement.

6. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: S2: The construction pressure is higher than the safety pressure, the starting pressure rate is 0.005 - 0.1 Mpa / min, and the starting pressure amplitude < 5 Mpa; S3: Add 50 - 100 Kg of 30 / 200 mesh in-seam temporary plugging agent.

7. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: S2: The pressure rising rate > 0.1 Mpa / min or the pressure rising amplitude > 5 Mpa; S3: Reduce the displacement to 1 - 2 m 3 / min, and add 150 - 200 Kg of 4 / 200 - mesh inter - cluster temporary plugging agent.

8. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 1, characterized in that: In S2, the starting pressure situation of the adjacent well and the construction displacement of the fracturing well rise and fall simultaneously. It is necessary to reduce the scale of the pumping construction. At the same time, for the well sections with similar geological conditions and greater interference possibility in the subsequent construction, before fracturing, this section should be temporarily plugged in advance.

9. A fracturing adjustment method based on the pressure response of adjacent wells according to any one of claims 7 or 8, characterized in that: For the well sections with similar geological conditions and greater interference possibility in the subsequent construction, before fracturing, this well section should be temporarily plugged in advance, and the preferential liquid intake channels should be blocked in advance to avoid the initial fracture communication.

10. A fracturing adjustment method based on the pressure response of adjacent wells according to claim 9, characterized in that: The way of temporary plugging in advance is to add inter-cluster temporary plugging materials after acidizing.

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