A method for fishing a cased hole lateral

Abstract

The present application relates to a kind of fishing oil layer casing open hole sidetracking method, belong to petroleum drilling completion technical field.The specific steps are as follows: for the characteristics of different types of reservoir, establish fine geological model, quantitatively study the distribution of remaining oil;The oil layer casing is taken out from downhole, surface casing is retained, while introducing navigation gyroscope not affected by magnetic interference, avoid random windowing state in downhole;From the wellhead, use special tools to complete one windowing, repair window;According to the lithology and trajectory control requirements, select drilling assembly and directional tool, use wireless drilling instrument or wired drilling instrument, scientific control full angle change rate, accurately control well trajectory, new oil layer casing is lowered in the surface casing below the original wellbore.According to different types of reservoir, formulate targeted sidetracking completion method.The present application utilizes existing resources, reduces capital investment, mainly reduces drilling footage, utilizes existing ground pipe network and equipment, reduces land acquisition and other tedious work.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for fishing oil layer casing open hole sidetracking, and belongs to the technical field of oil drilling and completion. BACKGROUND

[0002] The open hole sidetracking method is to inject a cement plug in the wellbore, and a new wellbore is sidetracked through the cement plug. In order to successfully sidetrack the new wellbore, the cement plug as a support platform must have sufficient strength, otherwise it cannot provide the necessary support for sidetracking. This is particularly important for hard formations, because if the strength of the cement plug is not enough, the drill bit will drill through the cement plug without sufficient support, resulting in the failure of sidetracking; especially in deep wells, abnormal formation high temperature, wellbore shrinkage and large belly will all cause poor quality of the cement plug. Sidetracking is a process of deviating the drilling trajectory of the drill bit from the original wellbore trajectory according to the pre-design, based on the original wellbore trajectory (straight well, directional well, horizontal well), using special sidetracking tools.

[0003] In view of the actual situation that the number of casing damage and falling objects increases, the well condition deteriorates, and the utilization rate of oil wells decreases in the later stage of oilfield development, and in view of the characteristics of high requirements for new well drilling machines, long well construction period, high land acquisition cost and high pre-drilling cost in the aspects of developing difficult-to-produce reserves and increasing reserves and production, the present application proposes an oil layer surface casing open hole sidetracking technology. SUMMARY

[0004] The present application discloses a method for fishing oil layer casing open hole sidetracking, aiming at engineering abandoned wells, low-yield and low-efficiency wells, tapping the potential of remaining oil, increasing recoverable reserves, and improving the development level of the block.

[0005] The technical solution adopted by the present application is a method for fishing oil layer casing open hole sidetracking, and the specific steps are as follows:

[0006] Step one, according to the characteristics of different types of oil reservoirs, a fine geological model is established, and the distribution of remaining oil is quantitatively studied;

[0007] Step two, the oil layer casing is taken out from the downhole, the surface casing is retained, and a navigation gyroscope that is not affected by magnetic interference is introduced to avoid random windowing in the downhole; the window is opened at the wellhead, and a special tool is used to complete one-time windowing and window repair;

[0008] Step three, according to the requirements of formation lithology and trajectory control, the drilling tool assembly and directional tool are selected, wireless or wired drilling instruments are used, the full-angle change rate is scientifically controlled, and the wellbore trajectory is accurately controlled, and a new oil layer casing is run in below the surface casing in the original wellbore;

[0009] Step four, a targeted sidetracking completion method is formulated for different types of oil reservoirs.

[0010] Further, the step one specifically comprises establishing a fine geological model by using Petrel software for different types of reservoir characteristics, describing the reservoir structure characteristics, sedimentary facies, oil layer, porosity, permeability plane and longitudinal distribution, and dividing the reservoir into several grids, and quantitatively calculating the remaining reserves through the difference between the reserves and cumulative oil production of each grid, and determining the remaining oil distribution.

[0011] Further, the step one is based on the Petrel geological model, and a numerical model is established to predict the capacity of the sidetracking well through numerical simulation.

[0012] Further, the step two specifically comprises a whipstock and a milling cone.

[0013] Further, the step three considers factors including quality, technology, safety and environmental protection when selecting the drilling assembly and the directional tool.

[0014] Further, the step one needs to meet the following conditions when predicting the capacity of the sidetracking well:

[0015] (1) Reservoir implementation: the deployment target is located in the favorable part of the sedimentary facies, the vertical well oil layer thickness is greater than 20 meters, the distance from the fault is more than 50 meters, and the distance from the edge water is more than 100 meters;

[0016] (2) Reasonable well spacing: deployed between wells, the distance from the original well is more than 50 meters, and the reasonable well spacing is maintained with the surrounding wells.

[0017] Further, the step one needs to meet the following conditions when predicting the capacity of the sidetracking well:

[0018] (3) Remaining oil: the deployment area has a lower recovery degree than the whole block index, and the regional remaining recoverable reserves are greater than 3000 tons;

[0019] (4) Technically and economically feasible: the old well can be implemented by sidetracking with casing failure, falling objects or no remaining layers, the sidetracking parameter design can be realized in engineering, and the predicted economic benefit index is good.

[0020] Further, the step four comprises the methods of tailpipe cementing and completion, upper cementing, lower screen pipe and gravel packing completion.

[0021] The present application discloses a method for salvaging oil layer casing open hole sidetracking, which has the beneficial effect that the present application utilizes existing resources such as abandoned wells, low-yield and low-efficiency old wells, reduces capital investment, mainly reduces drilling footage, utilizes existing ground pipe network and equipment, and reduces tedious work such as land acquisition. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0023] Figure 1 The figure shows a schematic diagram of the original well;

[0024] Figure 2 The figure shows a schematic diagram of the downhole after fishing the oil layer casing in Example 1;

[0025] Figure 3 The figure shows a schematic diagram of the downhole after implementing the sidetracking in Example 1.

[0026] The figure shows:

[0027] 1, surface casing; 2, original well oil layer casing; 3, production well perforated well section; 4, residual position; 5, sidetracked well oil layer casing. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application.

[0029] In order to further understand the inventive content of the present application, the present application will be further described below in combination with the specific embodiments.

[0030] Example 1:

[0031] On the basis of the developed well pattern of the oil reservoir, find the old well which can be used, such as Figure 1 The figure shows a schematic diagram of the downhole after fishing the oil layer casing in Example 1; The figure shows a schematic diagram of the downhole after implementing the sidetracking in Example 1. Figure 2 The original well oil layer casing 2 is taken out from the downhole, the residual position 4 is left after fishing the original well oil layer casing 2, the surface casing 1 is retained in the original position, and the oil layer distribution and the production situation of the surrounding well are combined, such as Figure 3As shown, the oil layer casing 5 is sidetracked to the target layer. Specifically, for different types of reservoir characteristics, a fine geological model is established by using Petrel software to describe the structural characteristics, sedimentary facies, oil layer, porosity, permeability plane and longitudinal distribution of the reservoir, and the reservoir is divided into several grids. The remaining reserves are quantitatively calculated by the difference between the reserves and cumulative oil production of each grid, and the remaining oil distribution is determined. On the basis of the Petrel geological model, a numerical model is established, and the productivity of the sidetracked well is predicted by numerical simulation.

[0032] The oil layer casing is taken out from the downhole, and the surface casing 1 is retained, while a navigation gyroscope that is not affected by magnetic interference is introduced to avoid the random windowing state in the downhole; the window is opened from the wellhead, and special tools such as a deflecting device and a milling cone are used to complete one-time windowing and window repair; according to the requirements of stratum lithology and trajectory control, the drilling tool assembly and directional tools are selected by comprehensively considering quality, technology, safety and environmental protection, wireless or wired drilling instruments are used, the full-angle change rate is scientifically controlled, and the well trajectory is accurately controlled, and the new oil layer casing is run in the original wellbore below the surface casing 1. Different types of reservoirs are formulated for targeted sidetracking completion methods, mainly including methods such as tailpipe cementing completion, upper cementing, lower screen pipe and gravel packing completion.

[0033] Further, the following conditions need to be met in step one by predicting the productivity of the sidetracked well:

[0034] (1) Reservoir implementation: The target is deployed in the favorable part of the sedimentary facies belt, the oil layer thickness of the vertical well is greater than 20 meters, the distance from the fault is more than 50 meters, and the distance from the edge water is more than 100 meters;

[0035] (2) Reasonable well spacing: Deployed between wells, the distance from the original well is more than 50m, and the well spacing with the surrounding wells is reasonable.

[0036] (3) Remaining oil is known: The deployment area has a lower recovery degree than the whole block index, the regional remaining recoverable reserves are greater than 3000 tons, and the target layer of the oil well has a high yield before production;

[0037] (4) Technically and economically feasible: The old well can be implemented by sidetracking with casing failure, falling objects or remaining layers, the sidetracking parameter design can be realized in engineering, and the predicted economic benefit index is good.

[0038] By using the method of the present application, new area evaluation and boundary exploration are accelerated, cost savings and benefits are created, difficult-to-recover reserves are utilized, and old area expansion well deployment is promoted. In view of the problems in the traditional development concept that the sidetracking technology is only single applied to interwell remaining oil tapping and the implementation target of layer series interchanging is limited, and the effect is gradually deteriorating, by adjusting the deployment idea, the transformation of multiple targets, multiple purposes and multiple fields such as perfecting well pattern, implementing productivity, adding reserves and considering oil and gas is realized.

[0039] From 2012 to 2014, 429 well times were implemented in three blocks, and the cumulative oil increment was 562,000 tons. Table 1 is a classification table of different implementation targets of sidetracking wells from 2012 to 2014. The change of sidetracking well deployment ideas and the diversification of deployment targets play an important role in relieving the decline of old blocks, making up for the shortage of new wells, and promoting exploration and increasing reserves. Compared with the implementation of new wells, sidetracking wells save investment by about 1 / 2-2 / 3.

[0040] Table 1: Classification table of different implementation targets of sidetracking wells from 2012 to 2014

[0041]

[0042] The old well L66C is used to explore the new area reserves, and Table 2 is a comparison table of investment details of sidetracking well L66C and new well L81. Compared with the exploration well L81, the investment is saved by 1.35 million yuan (drilling investment 950,000 yuan, saving 400,000 yuan of land acquisition and compensation well site fee, saving 30,000 yuan of casing and Christmas tree.)

[0043] Table 2: Comparison table of investment details of sidetracking well L66C and new well L81

[0044]

[0045] For the difficult-to-produce reserves area, the sidetracking technology is used as the starting point of development and deployment, and the gravel packing completion technology is first introduced. Table 3 shows the application of sidetracking technology in the difficult-to-produce reserves of W83 block, which brings out 14 new well locations, develops 1.2 million tons of geological reserves, and realizes the overall development of the difficult-to-produce block.

[0046] Table 3: Application of sidetracking technology in the difficult-to-produce reserves of W83 block

[0047]

[0048] The present application is mainly aimed at old oilfields such as long-term production, steam injection, measures, workover, casing damage, and poor well conditions; with the decrease of oilfield development output, the effect of capacity wells is getting worse year by year, the replacement of oilfield reserves is getting more difficult, and the stable production situation of oilfields is severe. Through years of field practice experience, sidetracking well deployment must meet the three conditions of controllable geological body, knowable remaining oil, and technically and economically feasible, and the optimization design concept of sidetracking well is formed, which effectively guides the sidetracking well plan deployment.

[0049] The present application utilizes existing resources such as abandoned wells, low-yield and low-efficiency old wells, reduces capital investment, mainly reduces drilling footage, utilizes existing ground pipe network and equipment, and reduces tedious work such as land acquisition.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of fishing a cased hole sidetrack in a producing oil zone, characterized by, The specific steps are as follows: Step one, according to the characteristics of different types of reservoir, establish a fine geological model, quantitative study of remaining oil distribution; Step two, the oil layer casing is taken out from the downhole, the surface casing is reserved, and the navigation gyroscope which is not affected by magnetic interference is introduced to avoid the random windowing state in the downhole; The position (4) is the position after fishing the original well oil layer casing (2), the window is opened from the remaining position (4) below the surface casing, and the special tool is used to complete the one-time windowing and windowing; Step three, according to the requirements of stratum lithology and trajectory control, select the drilling tool combination and directional tool, use wireless drilling instrument or wired drilling instrument, scientifically control the full angle change rate, accurately control the well trajectory, and lower the new oil layer casing below the surface casing in the original wellbore; Step four, develop targeted sidetracking and completion methods for different types of reservoirs.

2. A method of open hole sidetracking of a cased hole production interval according to claim 1, characterized in that, Step one, specifically includes, according to the characteristics of different types of reservoir, using Petrel software to establish a fine geological model, describing the reservoir structure characteristics, sedimentary facies state, oil layer, porosity, permeability plane and longitudinal distribution, and dividing the reservoir into several grids, calculating the remaining reserves through the difference between the reserves and cumulative oil production of each grid, and determining the remaining oil distribution.

3. A method of sidetracking a cased hole by milling a reservoir casing in accordance with claim 2, wherein, Step one, on the basis of establishing a fine geological model in Petrel software, establish a numerical model, and predict the sidetracking well productivity through numerical simulation.

4. The method of claim 1 wherein, Step two, the special tool specifically includes a deflector and a milling cone.

5. The method of claim 1 wherein, Step three, the factors to be considered in selecting drilling tool combination and directional tool include quality, technology, safety and environmental protection.

6. A method of sidetracking about a production casing in a reservoir according to claim 3, characterized in that, The following conditions must be met when predicting the productivity of sidetracking wells in step one: (1) Reservoir implementation: the deployment target is located in the favorable part of the sedimentary facies belt, the straight well oil layer thickness is greater than 20 meters, the distance from the fault is more than 50 meters, and the distance from the edge water is more than 100 meters; (2) Reasonable well spacing: deployed between wells, more than 50 meters away from the original well spacing, and maintain reasonable well spacing with surrounding wells.

7. A method of open hole sidetracking of a cased hole production interval according to claim 6, characterized in that, The following conditions must be met when predicting the productivity of sidetracking wells in step one: (3) Remaining oil is known: the deployment area has a lower recovery degree than the full block index, and the regional remaining recoverable reserves are greater than 3000 tons; (4) Technically and economically feasible: the old well can be implemented for sidetracking with casing failure, falling objects or no remaining layers, the sidetracking parameter design can be realized in engineering and the predicted economic benefit index is good.

8. A method of sidetracking about a production casing in a reservoir according to claim 1, characterized in that, Step four, developing targeted sidetracking and completion methods for different types of reservoirs specifically includes the methods of tailpipe cementing and completion, upper cementing, lower screen pipe and gravel packing completion.

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