Application of annulus pressure control valve

Some blocks of Tahe Oilfield are typical heavy oil reservoirs, which have the characteristics of high density, high viscosity and poor mobility According to statistics, the viscosity Zui of surface crude oil is as high as 18 × 104mpa? S (60 ℃) The key of heavy oil recovery is to reduce the viscosity of crude oil and improve the fluidity of crude oil In Tahe work area, the mining method of blending with dilution and reducing viscosity is often adopted There are two types of completion production string in Tahe heavy oil well: light string and string with packer As there is no packer for the smooth string, the mixing operation can be directly carried out at the bell mouth; for the string with packer, the packer will separate the annulus up and down In order to meet the requirements of mixing production, it is necessary to design the mixing sliding sleeve at the upper part of the packer to ensure the smooth mixing channel The conventional sliding sleeve is mainly composed of outer cylinder, mandrel (including seal), ball seat (including reducing mechanism) and two flow channels (channel A and channel B) Among them, channel a is the valve hole connecting the oil pipe and the annulus; channel B is the internal channel of the sliding sleeve, as shown in Figure 1 Fig 1 mixed thin sliding sleeve structure: when entering the well, flow channel a is blocked by the sealing mechanism on the mandrel, and flow channel B is smooth, which can be used for well washing, mud displacement and other operations To test production, it is necessary to throw a ball to open flow channel a, put a ball of corresponding size into the oil pipe, pressurize the oil pipe, push the mandrel down, expose channel a, connect the oil pipe with the annulus, and then carry out dilution operation; after that, continue to pressurize the oil pipe until the ball socket is knocked out, so that flow channel B is unblocked again, and the heavy oil from the formation flows to a When mixed with dilute oil, the viscosity of crude oil can be reduced For heavy oil wells with serious leakage, considering the safety of well control, drilling is usually stopped to directly test production On the one hand, the test string needs to meet the requirements of dilution; on the other hand, if the test effect is not good, it needs to be reformed by acid pressure, and the test string needs to meet the requirements of acid pressure The conventional sliding sleeve has a reducing mechanism, which has a certain impact on the transformation effect In order to overcome this deficiency and meet the requirements of dilute production and the possible acid pressure construction in the later stage, the annulus pressure control valve is developed and has achieved good application effect 1 Annular pressure control valve 1.1 structure design The structure of annular pressure control valve is shown in Figure 2, which is composed of upper joint, O-ring seal, valve hole, shear pin, outer sleeve, self-locking mechanism, movable valve body and lower joint, etc 1-upper joint; 2-o-ring; 3-valve hole; 4-shear pin; 5-movable valve body; 6-outer sleeve; 7-self-locking mechanism; 8-lower joint Figure 2 Structure of annular pressure control valve 1.2 working principle: when the annular pressure control valve enters the well, the valve hole is closed, at this time, the oil pipe and the annulus are not connected When the lost circulation well needs to be replaced with slurry or the acid killing well needs to be mixed with thin oil test, the valve hole of the control valve needs to be opened to pressurize from the annulus The pressure acts on the pressure bearing end face of the movable valve body, and the pressure on the pressure bearing end face can be transmitted to the shear pin When the pressure on the pressure bearing end face exceeds the shear force of the shear pin, the shear pin breaks, and the annulus pressure pushes it to move The valve body moves downward and the valve hole gradually exposes There are ratchets on the outer surface of the movable valve body and the inner surface of the self-locking mechanism When the movable valve body moves downward to the surface and the ratchets of the self-locking mechanism engage with each other, the valve hole is completely opened; at the same time, the movable valve body remains fixed due to the self-locking structure, and the flow channel between the oil pipe and the annulus is formed 1.3 technical features 1) the ratchet is firmly engaged The external ratchet of the movable valve body inclines upward, and the internal ratchet of the self-locking structure inclines downward The two are tightly engaged, which can effectively fix the movable valve body 2) the design of shear pin is flexible According to the depth of annulus pressure control valve, the density of kill mud and the setting requirements of packer, appropriate number of pins can be selected to meet the construction requirements 1.4 main technical parameters: the common annular pressure control valve Zui in Tahe oilfield has a large outer diameter of Φ 127mm, a small inner diameter of Φ 61mm, a total length of 0.78m, a working temperature of 150 ℃, and a suitable casing inner diameter of Φ 152-Φ 168mm 1.5 scope of application: the annulus pressure control valve has the characteristics of annulus pressure control and large internal diameter Combined with the actual working conditions of Tahe oilfield, it can be used in the following operations: 1) well killing operation Similar to the commonly used well killing slide sleeve, when the well is first put into the well along with the completion string, and later workover operation is carried out, if the wellbore is blocked and the circulation cannot be established, the valve hole can be opened by pressurizing the annulus to establish a well killing circulation channel 2) at present, the heavy oil mixed with thin Tahe Oilfield mostly applies it to the mixing operation After the control valve hole is opened, the mixing of heavy oil and mixed with thin oil can be realized, so as to achieve the purpose of viscosity reduction 2 Field application well th245ch is a heavy oil sidetracking horizontal well in the main area of Tahe oilfield, with a four open well structure In order to avoid water, the sidetracking point is raised, the expansion pipe is lowered into the third spud for cementing and completion, and the Φ 120.65mm bit is used for open hole completion in the fourth spud The well needs to be reconstructed and evaluated in different layers, and the production needs to be diluted In order to meet the requirements of acid pressure and dilution at the same time, packer and annulus pressure control valve are installed in the string 2.1 string structure: the combination of acid fracturing completion string of the well is: tubing + annulus pressure control valve + casing packer + tubing + hydraulic anchor + open hole packer + ball seat + screen pipe + round head blind plugging guide shoe, in which the casing packer and open hole packer are hydraulic packers, which need to be thrown; pressure setting As shown in Figure 3 Figure 3 th245ch well structure The open hole packer is used to seal the upper open hole section, so that the fracturing fluid only acts on the lower reservoir section; the hydraulic anchor is mainly used for anchoring, to protect the open hole packer and the oil pipe during the acid fracturing construction; the screen pipe and the round head blind plugging guide shoe are used together to catch the ball seat lost and avoid falling objects underground; the casing packer is used to pressurize the annulus and open the annulus pressure control Protect the lower expansion pipe during valve making 2.2 construction steps 1) in order to smoothly run in the completion string in the later stage, conduct wellbore treatment such as pipe scraping, well passing and simulated well passing 2) remove the wellhead, put in the completion string of acid fracturing and install the Christmas tree 3) slurry replacement, well flushing, setting packer, sealing inspection: after connecting the pressurized pipeline, pressurize the string step by step, 5.0, 8.0, 11.0, 14.0, 17.0, 20.0Mpa, and then release the pressure to 0 after 3min of each pressure stabilization Repeat the step-by-step positive pressure once again, and then release the pressure to 0 after 3min of each pressure stabilization After that, the open hole packer and casing packer are completely set; after that, the annulus is pressurized to 15.0mpa, the pressure is stabilized for 15min without pressure drop, the seal is qualified, and the pressure of the sleeve is relieved to 5.0mpa; then the positive pressure is pressurized to 0-22.0mpa to 19mpa, indicating that the setting ball seat is shot down, and the annulus pressure control valve is still closed 4) acid pressure construction: the pump pressure is 17.4-93.1mpa, the casing pressure is 4.7-19.2mpa, and the displacement is 0.5-5.9m3/min; a total of 655m3 of liquid is injected into the formation, and the total liquid volume is 625m3; the pressure drop is measured after stopping the pump for 20min, and the pump pressure is reduced from 17.4mpa to 17.0mpa, and the packer is well seated during acid pressure construction, effectively protecting the annulus 5) test and production: after heavy oil is seen, carry out the surface test process First, squeeze a thin oil with the volume of tubing into the well, squeeze the heavy oil back to the formation, and then pressurize the annulus to open the control valve: pressurize 3.8, 32.0, 18.0 and 3.8mpa successively from the annulus, and then open the control valve for the pressure drop display, and then carry out the production of thin oil 2.3 working condition analysis 1) the inner diameter of the annulus pressure control valve is 61mm, almost the same as the inner diameter of Φ 73.0mm (inch) oil pipe (62mm), realizing the large diameter of the pipe string; the high pump pressure of Zui and the large displacement of Zui are 93.1mpa and 5.9m3/min respectively, which is conducive to acid pressure construction 2) after the packer is set, the pressurization pressure of the annulus is 15MPa during seal inspection, and the opening pressure of the valve hole of the annulus pressure control valve is 32Mpa The pressure difference is large, which is conducive to field operation The pressure settings of the packer and the control valve do not interfere with each other and can work normally 3 Conclusion 1) there is obvious reducing mechanism in the conventional sliding sleeve, which limits the pump pressure and displacement of acid fracturing construction, and affects the effect of reservoir reconstruction 2) the annulus pressure control valve adopts the way of annulus pressurization, which saves the time of throwing and waiting for the ball to be put into the seat, and avoids the problem of opening in the middle of the way caused by misthrowing the steel ball or the sealing of the ball seat after pressurization for many times It can replace well killing or mixing thin sliding sleeve for well killing or mixing thin heavy oil in Tahe oilfield 3) the successful application of the annulus pressure control valve in th245ch well shows that the performance of the control valve is reliable and can meet the requirements of acid pressure and dilution operation in Tahe heavy oil well.