Background technology
In the orientation well, fractured horizontal well yield-increasing technique process of shale oil gas, low permeability reservoir, often use the set segmented fracturing technique of multistage cunning. Ball-throwing type fracturing sliding bush, as the crucial workpiece in staged fracturing technology, relies on well head to drop into diameter successively and suppresses pressure ball by little to big, opened by each section of sliding cover successively, then carry out follow-up pressing crack construction. After whole payzone pressure break terminates, suppress pressure ball under reservoir pressure effect, return discharge well head, if the row of returning is smooth, then enters down drilling tool and by ball seat and suppress pressure ball and jointly bore, be beneficial to later stage oil gas well liquid loading. Existing suppress pressure ball, easily it is out of shape when shaft bottom presses, affect and suppress pressure effect and the row of returning smoothly, and horizontal well toe end minor diameter is suppressed pressure ball to return row's difficulty big, enters drilling tool and carries out milling, cause construction period to extend, increase construction cost and risk under often needing.
Summary of the invention
It is an object of the invention to propose the solvable of a kind of shale gas well staged fracturing use and suppress pressure ball making method, the row of returning or milling is needed to suppress the problem of pressure ball during to solve staged fracturing in prior art, it is achieved to suppress the object that pressure ball can carry out controlled dissolving in subsurface environment.
The present invention is achieved through the following technical solutions:
What shale gas well staged fracturing used solvable suppresses a pressure ball making method, and the method comprises following operation: crystal grain diameter as nucleome crystal (1), is that the Al of 10 ��m is or/and Al by (a) by the metal magnesium powder of crystal grain diameter between 60 ~ 100 ��m2O3Powder, as housing crystal (2), carries out nucleocapsid coated, obtains composite powder; B () adds �� phase metal-powder (3) to, in composite powder, mixing; C () adds Alloy Forming agent and is mixed to evenly, powder is placed in mould and press forming; D the base substrate of press forming is heated to 400 ~ 600 DEG C by () in vacuum furnace, then be cooled to room temperature, obtains the blank of material completed; E the blank of material completed is made as spherical by (). The problem of pressure ball is suppressed for prior art needs the row of returning or milling when staged fracturing, the present invention provides the solvable of a kind of shale gas well staged fracturing use and suppresses pressure ball making method, what use present method was made suppresses pressure ball, the requirement of resistance to high pressure and solubilized can be met, it is achieved suppress the object that pressure ball can carry out controlled dissolving in subsurface environment.
The present invention uses the nucleome material that metal M g suppresses pressure ball for making, the standard potential of metal M g is-2.37V, corrosion potential is generally between+0.5 ~-1.65V, corrosion mainly generates more stable divalence Mg product with the Mg ion of unit price and water reaction, owing to being all rich in Cl in fracturing liquid and local water��, so reaction can be occurred further to generate MgCl2And hydroxide ion, thus make metallic surface that electrocorrosion occur rapidly, this reaction process is as follows:
Mg+H++H2O��Mg2++OH��+H2
Mg(OH)2+2Cl����MgCl2+2OH��
The matrix grain suppressing pressure ball described in making crosses the conference reduction strength of materials, it is unfavorable for suppressing the load performance of pressure ball, and the little cost that increases crossed by crystal grain, it is preferred to the nucleome crystal grain diameter of described metal M g is in 60 ~ 100 �� m, under the prerequisite ensureing its intensity and pressure-bearing, reduce production cost as far as possible.
In addition, it may also be useful to crystal grain diameter is that the Al of 10 ��m is or/and Al2O3Powder as housing crystal, by magnesium powder and aluminium powder or/and Al2O3It is coated that powder carries out nucleocapsid, to ensure the controlled of solubility property. Described housing crystal is being rich in Cl��Electrolyte solution in erosion rate lower than described body material, namely form electrochemical corrosion potential difference between housing crystal and metal M g, so that before the work completing to suppress pressure and opening sliding cover, suppressing pressure ball and can not start rapid electrolysis. If described case material is too thin, be unfavorable for the control of erosion rate, take again if too thick volume excessive be not easy to preparation and electrolysis generation speed excessively slow, be therefore optimum thickness when experiment show that its thickness is 10 ��m. In addition, �� phase metallic element in the gap of described case material, it is evenly distributed with, by the dispersion-strengthened action of the �� phase metallic element of high-temperature stable, it is to increase suppress the compressive strength of pressure ball. By the way, to ensure to suppress intensity and the solubility property of pressure ball. Afterwards, add Alloy Forming agent and it is mixed to evenly, powder is placed in mould and press forming; The base substrate of press forming is heated to 400 ~ 600 DEG C in vacuum furnace, in heat-processed, Mg and Al/Al2O3The aggregate of metal powder granulates is turned into the agglomerate of metal grain, and the intensity of sintered compact increases. It is cooled to room temperature again, obtains the blank of material completed; The blank of material that completes is cut as spherical, namely obtain high strength, solubilized suppress pressure ball.
Preferably, described step (a) uses the nucleocapsid ratio of 1:1. Namely the ratio of described nucleome crystal and housing crystal is 1:1, so that housing crystal can obtain fully coated, makes to suppress the dissolving of pressure ball in down-hole and occurs slowly to start, to improve controllability.
Preferably, described �� phase metal-powder is Fe and/or Cu. The beta phase structure of Fe and Cu is easy to obtain.
The present invention compared with prior art, has following advantage and useful effect:
What the present invention's a kind of shale gas well staged fracturing used solvable suppresses pressure ball making method, with the use of the metal M g powder of crystal grain diameter 60 ~ 100 ��m as nucleome crystal, it may also be useful to diameter is that the Al of 10 ��m is or/and Al2O3Powder is as housing crystal, and add �� phase metallic element wherein to mixing, press forming, and in vacuum furnace, it is heated to 400 ~ 600 DEG C, to be cooled cutting to room temperature is polished as spherical, what can obtain can dissolving gradually in down-hole suppresses pressure ball, needs the row of returning or milling to suppress the problem of pressure ball, it is achieved to suppress the object that pressure ball can carry out controlled dissolving in subsurface environment during to solve staged fracturing in prior art.
Embodiment 1:
The solvable of a kind of shale gas well staged fracturing use as shown in Figure 1 suppresses pressure ball making method, the method comprises following operation: crystal grain diameter as nucleome crystal (1), is that the Al of 10 ��m is or/and Al by (a) by the metal magnesium powder of crystal grain diameter between 60 ~ 100 ��m2O3Powder, as housing crystal (2), carries out nucleocapsid coated, obtains composite powder; B () adds �� phase metal-powder (3) to, in composite powder, mixing; C () adds Alloy Forming agent and is mixed to evenly, powder is placed in mould and press forming; D the base substrate of press forming is heated to 400 ~ 600 DEG C by () in vacuum furnace, then be cooled to room temperature, obtains the blank of material completed; E the blank of material completed is made as spherical by (). In the present embodiment, the pressure ball of suppressing using aforesaid method to make diameter 38.1mm is carried out finite element Mathematical Model Analysis, wherein selected pure magnesium powder Young's modulus 44.8GPa, Poisson's ratio 0.35, ball seat body internal diameter 35mm. Modal analysis results shows, and when spheroid bears 70MPa pressure, maximum stress place is the point of contact of spheroid and ball holder surface, and its maximum stress value is 288MPa. And this is suppressed pressure ball and carries out compressive property test and obtain, its maximum resistance to compression ability has all exceeded 300MPa, is greater than the theoretical contact stress suppressing pressure ball and ball seat under 70MPa pressure. Therefore, suppressing, in the present embodiment, the bearing requirements that pressure ball can meet 70MPa, the conventional stratum for non-abnormal pressure all can use. In addition, the pressure ball of suppressing using aforesaid method to make being placed in 85 DEG C, the KCl solution of mass concentration 3%, under simulation well, situation has carried out dissolubility test. After tested, dissolution rate reaches 0.2g/h and stablizes. Thus, to solve staged fracturing in prior art the row of returning or milling is needed to suppress the problem of pressure ball time, it is achieved to suppress the object that pressure ball can carry out dissolving in subsurface environment.
Above-described embodiment; the object of the present invention, technical scheme and useful effect have been further described; it is it should be understood that; the foregoing is only the specific embodiment of the present invention; the protection domain being not intended to limit the present invention; within the spirit and principles in the present invention all, any amendment of making, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.