Horizontal well mining technology has the advantages of increasing the oil drainage area of ​​oil and gas wells, delaying the bottom water coning to improve oil and gas well production and recovery, increasing recoverable reserves, developing thin layers and difficult to move reservoirs, etc. Recovery and new oilfields are an important technology for the development of less wells. In recent years, Binnan Oil Production Plant has continuously improved the horizontal well development technology, and formed a series of horizontal well mining supporting technologies such as open-hole screen completion, pickling to remove mud cake blockage, bottom filling sand control, uniform steam injection, and lifting support. It has played a positive role in improving the production efficiency of horizontal wells.
First, the status quo of horizontal well mining technology
With the continuous expansion of the application scale of horizontal wells, the horizontal well mining technology has also developed rapidly. Through continuous improvement and matching, four supporting mining technologies have been gradually formed.
1. Cementing completion technology for open hole screen completion project
The technology utilizes a naked eye packer. Special completion tools such as grading hoops, blind slabs, and well washing valves are used to grout cement in horizontal wells. According to the reservoir conditions, one-hole completion of the oil layer is completed by using open-hole packers and large-diameter screens. Well technology has strong adaptability and advantages, and its advantages are reflected in the following points:
1 Cementing above the oil layer section, high-efficiency sealing of the interference layer of the inclined section.
2 The oil layer section is not cemented, and the completion of the screen is used to avoid the pollution of the oil layer by the cementing, and avoid the secondary pollution of the oil hole by the perforation, and also save the perforation cost.
3 The large-hole precision microporous filter tube is used in the naked eye section, which can effectively slow down or prevent sand and blockage of the oil layer. After the completion of the well, the inner diameter of the pipe string is large, and the base pipe is 4177.8mm manure pipe, which facilitates the entry of the pipe string in the later stage, which reduces the difficulty of the operation of the oil well in the later stage.
4 The long section is segmented by the outer packer to achieve segmental mining of the oil layer.
5 Well washing and seat sealing packer is completed once, and the construction is simple and feasible.
2. Pickling to remove mud cake blocking technology
In order to release the mud cake and mud blockage during the drilling process, the oil flow channel was communicated and a horizontal well pickling process was implemented. Through the multi-stage bowl packer, the acid is forced into the formation to react with the blockage, and residual acid and plugs are discharged through the bottom well valve. The use of a multi-stage bowl packer maximizes the cleaning of plugs around the screen and increases the permeability of the near well.
3. Thermal recovery horizontal well uniform steam injection technology
The steam outflow point of the horizontal well-injection steam injection process is too concentrated, causing too much steam absorption in the local formation, which affects the suction of the entire horizontal section. At the same time, after multiple rounds of steaming, the steam will preferentially enter the heated or depleted channels, so that the formation will be unevenly sucked, which will easily cause premature steam or flooding of the well. To this end, a multi-point uniform steam injection pipe column has been applied to achieve uniform steam injection in the horizontal section, which improves heat utilization and oil layer utilization.
4. Single 113 super heavy oil HDCS mining technology
HDCS mining technology refers to horizontal well (Horizo ​​ntal Well + oil dissolver + C02 (Carbon dioxide) + sub-I critical steam (Steam) mining technology, C02 has expansion, viscosity reduction, reducing oil-water interfacial tension, Improve the reservoir permeability and reduce the density of crude oil; oil-soluble viscosity reducer combined with CO, can improve the elastic energy of the formation, reduce the viscosity of crude oil in the near-well zone, and thus improve the development of ultra-heavy oil steam stimulation. Therefore, HDCS mining technology can expand steam heat volume, increase viscosity, increase energy and expand horizontal well drainage area, thereby increasing oil well productivity and providing a guarantee for the effective development and utilization of a single 113 super heavy oil.
2. Technical improvement and application
In the application process of horizontal well mining supporting technology, some problems were gradually exposed. In order to further improve the production effect of horizontal wells, Binnan Oil Refinery improved and improved some of the processes and achieved good results.
1. Improved application of pickling packers
In order to prevent the formation of suction during the washing of the packer, the conventional well-washing packer has five flow channels in the body. During the acid pickling process, most of the acid liquid directly passes through the flow cell to the bottom of the well. Then, through the sand control pipe, the well valve enters the oil pipe. It can not be completely washed and unblocked.
In order to improve the pickling effect, the pickling packer is improved: four flow holes are processed in the body of the well seal, and the flow hole is in the open state during the downhole process, and the pressurization is performed when the lower seal cannula enters the well wash valve. -3t, close the flow hole, during the pickling construction, under the action of the well seal, force the acid to pass through the formation; after the pickling construction, the pipe string is lifted up, the circulation hole is opened, and the oil sleeve is connected to the air and will not form. Suction.
2. Completion and production process improvement
In the past, most horizontal wells were completed with naked-eye screens, pickled and put into production, and certain effects were taken. However, from the effect of the horizontal wells put into operation in the first half of the Linfanjia oilfield, some wells showed low liquid and low yield, and the production results were not satisfactory. . In the horizontal wells of pickling and production, the wells of 9 Ping 10 and 12 wells in the injection and improvement area have better production results. 9 Ping 7 and 8 wells have a production effect due to sand production. The loss of the grading hoop of the 9 flat 9 well resulted in incomplete pickling and poor production results. The other 6 wells were not put into production. After analysis, in addition to problems in drilling and cementing processes, there are mainly the following reasons:
(1) Screen blockage
The horizontal wells in the Linfanjia oilfield are all equipped with a 4-layer screen structure. The filtration accuracy of the screen is basically selected according to the median value of the sand grain size of the formation sand (60% - 70%). The median sand grain size of the Linfanjia oilfield is 0.12mm, 80μm. Sand blocking accuracy). However, due to the difference in the particle size of the formation sand of each well, if the filtration accuracy is too small, the fine silt may be inlaid, the screen will be blocked, and the oil supply will be affected, and once the filter is clogged, it will be difficult to release.
(2) Low formation pressure
According to the pressure measurement of 9 pieces in the forest, the average formation pressure is 6.0 MPa, and the ground lamination drop is large, which is one of the reasons that affects the production effect of the oil well. The well betting and oil well transfer work in the scheme should be accelerated to supplement the formation energy.
(3) Loss of formation, pickling and plugging is not complete
Due to the loss of the formation, most of the acid leaked into the formation, resulting in unblocking and back-flowing. For example, the 9-inch-1 well pickling back-out outlet does not return liquid. In view of the unsatisfactory effect of pickling and production, gravel packing can improve the stability of the wellbore. A dense gravel layer can be filled around the sand control pipe to protect the sand control pipe, support the well wall, and improve the permeability of the near well zone. Reduce the effect of the skin factor; it can also inhibit the migration of fine sand in some formations, so that the oil well can maintain stable production for a long time.
Shanglin Oilfield is a reservoir with high fine sand content. The median sand particle size is 0.09-O.llmm. It is difficult to achieve good production results by using independent screen completion, pickling and production. Therefore, the horizontal wells put into operation in the late stage of Shanglin Oilfield are applied with open-hole screen completion, extra-tube extrusion sand control technology and casing perforation completion. In-pipe extrusion and sand control technology to improve the production efficiency of horizontal wells and prolong the production cycle. Through large displacement and high sand ratio filling, a high permeability sand retaining barrier is formed around the screen tube, and at the same time, the formation is modified, the permeability of the far well zone is improved, and the effect of the silt transport of the formation is inhibited. In addition, following the moderate sand control concept, the screen sand retaining precision is increased from 80μm to 120μm. Part of the fine sand is allowed to be discharged to reduce the blockage of fine silt.
Technical features of open hole screen completion and external pipe extrusion filling sand control technology: Reverse filling in horizontal section, simple process and high safety, can form a high permeability between stainless steel precision screen and wellbore annulus The sand barrier improves the conductivity of the near-well zone and improves production. Construction process: firstly, the service pipe column is opened to open the bottom filling channel, and then the mortar is pumped from the oil pipe. The sanding ratio is from small to large. Finally, the casing gate is opened to fill the stainless steel precision screen and the wellbore annulus when the pressure rises. When the height is high, stop adding sand; after the sand control is finished, lift the service pipe column, close the bottom filling channel, backwash the well, and wash out the excess mortar.
The casing perforation completion, the pipe extrusion and sand control technology can effectively penetrate the pollution zone caused by drilling and cementing, and form a high-permeability artificial sand wall in the near well zone. At the same time, the original primary sand barrier was changed into a three-level sand barrier, forming a continuous stable sand wall with three levels of formation, wellbore and precision sand filter, which weakened the fluid carrying fine sand to the screen; Strike, extending the life of the screen. Construction process: firstly put down the sand control pipe column, seat seal, throw the hand to wrap the packer, then open the service pipe column to open the bottom filling channel of the sand control pipe column, pump the mortar from the oil pipe to the ground layer to squeeze and fill, and finally open the casing gate pair The precision screen is filled with the casing annulus. When the pressure is increased to a certain value, the sanding is stopped. After the sand control is completed, the service pipe string is lifted, the bottom filling channel is closed, the well is washed, and the excess mortar is washed out.
3. Introducing concentric double pipe steam injection technology
The multi-point uniform steam injection technology of the horizontal well partially alleviates the contradiction of steam distribution, but due to the single pressure system, the problem of steam coning cannot be solved. Therefore, in order to achieve uniform distribution of steam in the whole section, reduce heat loss and improve heat insulation effect, this year, Binnan Oil Production Plant also introduced the horizontal double-tube steam injection process of horizontal wells in Liaohe Oilfield. The technical mechanism of the process is to form two pressure fields in the case of equal dryness distribution. When a certain steam injection intensity is reached, the pressure fields at both ends tend to be in equilibrium, and two mutually connected steam chambers are formed in the horizontal section, thereby Achieve the purpose of uniform distribution of steam throughout the entire period.
4. Horizontal wellbore lifting process package
In view of the current situation that horizontal wells are restricted by well inclination, shallow pump depth is shallow, and sinking is low, horizontal pump production technology has been introduced. The horizontal pump adopts multi-stage sealing units which are completely independent from each other, the stages are independent of each other, and the strong opening and closing are strong. The single sealing unit is in a free state with the center rod and the pole. When the horizontal section is lifted, the eccentric force of the pole is lifted. Acting on the guide block, the guide block is subjected to eccentric wear, which can effectively eliminate the eccentric wear of the downhole pump sealing unit. The pump has a strong sand discharge function, and is suitable for anti-discharge combined sand control technology and horizontal well pumping. Technical features: 1 Suitable for pumping position, the well inclination reaches 75. Suitable for high-angle wells and horizontal wells; 2 strong sand-carrying capacity, no sand card, 2% sand content can ensure normal production; 3 high pump efficiency, elastic gap seal, automatic compensation of seal gap, loss relative to ordinary pump ( The same gap level is reduced by more than 50%; 4 The overall structure of the plunger is multi-stage strong open and strong closed, and has anti-gas function.
In addition, through the use of pole anti-biasing technology, that is, supporting the anti-bending anti-wear pair, the same curvature solid lubrication centralizer to solve the problem of instability and bending of the rod tube.
Solid lubricant with a curvature oriented technologies: solid lubricating sliding rod stabilizer tubing wall face with three arcuate curved same curvature; the metal surface with an outer friction resistance between the solid lubricating coating, lowering a lower pipe rod 50%-60%; the number of reciprocating grinding can reach 7.5 million times and the maximum working temperature can reach above 260 °C.
Third, the horizontal well production effect
In 2011, Binnan Oil Production Plant increased the application of horizontal wells. A total of 106 horizontal wells were deployed in the new and old districts and low-grade blocks, including 76 heavy oil horizontal wells and 30 conventional heavy oil horizontal wells. As of November 10, 2011, a total of 79 horizontal wells were drilled and 55 pumps were put into operation. The initial average single well is 35.5/7.9/%; the peak value is 38.3/16.3/57. 5%; currently 35 wells are opened, the average single well is 28.1/8.66/69.4%. The cumulative oil production is58628t, and the average single well produces 1066t. The following is the production effect of the partition block.
1. 9 blocks in the forest
There are 19 new horizontal wells drilled in 9 forests, all of which have been drilled, and the completion technology is completed with open-hole screens. At present, 15 horizontal wells have been put into operation, with an initial average single well of 19.2/38/80.2%; the peak is 21.7/8.4/54%; at present, the average well is 13/4.7/72.4%, and the cumulative oil production is 12429t. Among them, 4 wells, such as 9 Ping 3 well, 11 well, 15 well and 17 well, were crushed and put into operation by screen extrusion, and the other wells were put into production by foam pickling. From the production effect, the initial production of the sand-filled sand-filled production well is obviously better than that of the pickling production well. Since some wells are put into production later, the production effect needs to be observed.
2. Still 12-41
There are still plans to drill 10 new horizontal wells in 12-41 blocks, all of which have been drilled, and the completion process is completed with open-hole screens (still wells are completed by casing perforation in 12 wells and 10 wells). At present, 5 horizontal wells have been put into operation, except for the wells of 12 flats and 5 wells. The initial average single well is 21.2/5/76.3%; the peak value is 14.9/8.4/43.6%; the block has lower viscosity due to higher crude oil, and the current average single well is 18.4/7.2/60.9%. The cumulative oil production is 108lt. The effect is better.
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