CN103048239A - Method for testing thermal stability of re-fracture plugging agent - Google Patents
Method for testing thermal stability of re-fracture plugging agent Download PDFInfo
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- CN103048239A CN103048239A CN 201110326272 CN201110326272A CN103048239A CN 103048239 A CN103048239 A CN 103048239A CN 201110326272 CN201110326272 CN 201110326272 CN 201110326272 A CN201110326272 A CN 201110326272A CN 103048239 A CN103048239 A CN 103048239A
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Abstract
The invention discloses a method for testing the thermal stability of a re-fracture plugging agent. The method comprises the steps of: a, preparing a re-fracture plugging agent solution for later use; b, adding a pre-crosslinking agent and an accelerant in the re-fracture plugging agent solution, wherein the raito of a pre-crosslinking polymer to a pre-crosslinking agent is 60:1 and the concentration of the accelerant is 0.01 percent; c, sealing in an experimental container; d, placing in a thermostated container; e, taking out at regular intervals, determining the property; and f, analyzing the thermal stability of the re-fracture plugging agent according to tested data. The method is capable of rapidly testing the thermal stability of the re-fracture plugging agent, is accurate in testing result, simple in testing steps, and low in testing cost, and provides data support for the synthesis of the fracture plugging agent.
Description
Technical field
The present invention relates to a kind of method of testing of thermal stability of refracturing blocking agent.
Background technology
Low-permeability oil deposit is to refer generally to the oil reservoir that the oil reservoir of permeability between 10-50 * 10-3 μ m2 consists of in China.Along with the continuous intensification of exploration and development degree, China's low-permeability oil pool total proven reserves and in the mining-employed reserves shared ratio more and more higher, keep and the promotion development of oil industry in the effect brought into play increasing.As take China National Petroleum Corporation (CNPC) as example, at the bottom of calendar year 2001, verify petroleum-in-place 145 * 108t, wherein hyposmosis reserves 44 * 108t accounts for 30%; Employ petroleum-in-place 110 * 108t, wherein hyposmosis reserves 21 * 108t accounts for 19%; Residue is verified and is not employed petroleum-in-place 35 * 108t, and wherein hyposmosis reserves 22 * 108t accounts for 62%.In the reserves of verifying then in the recent period, the shared ratio of hyposmosis reserves is larger, up to 65%～70%.How to employ and developed the low permeability oil field reserves, to the sustainable and stable development of China Petroleum with guarantee that the safe tool of China's oil is of great significance.
Low-permeability oil deposit is because reservoir properties is poor, and oil well output is low, and owing to complex pore structure, seepage state is unusual, causes its oil-field development feature and medium to high permeable oil reservoir to be very different, even the variation of matter occurs.LOW PERMEABILITY OILFIELD DEVELOPMENT has following essential characteristic:
(1) the oil well natural production capacity is low, just has commercial mining behind the fracturing reform and is worth;
(2) percolation law is not followed Darcy's law, has the starting pressure gradient;
(3) natural energy is little, and pressure, production declining are fast, and primary recovery rate is low;
(4) the water injection well water-intake capacity is low, and starting pressure and water injection pressure rise fast;
(5) liquid production index sharply descends behind the oil well water breakthrough, and the stable yields difficulty is very large.
Hydraulic fracturing technology has been widely used in the exploitation in low-permeability oil gas field as the major measure of well production increment, intensified injection of wells, for the stable yields of oil gas field has been made significant contribution.Improve near the seepage flow condition the shaft bottom by waterfrac treatment, linked up the oil gas gathering area and change the hydrocarbon flow flowing mode, improved Oil ﹠ Gas Productivity.The output of domestic hypotonic oil gas field and the output that obtains by the waterfrac treatment transformation are all increasing sharply year by year.
Through oil, gas, the well after the waterfrac treatment, owing to be subjected to the at that time restriction of fracturing technology, material, equipment tool, the reason such as it is little that scale is owed, and material selection is improper, and plant capacity is limited can cause the hydraulic fracture flow conductivity significantly to reduce and ineffective gradually; Some then selects improper because of the well layer or the operation reasons also fails effectively to pass through simultaneously long period of development, and the major oil gas field has entered the development phase of middle and high Water-cut Period, and the difficulty of stable high yield is increasing; To this class Oil/gas Well, in order to obtain high yield and economic exploitation benefit, need to carry out refracturing.
Refracturing refers to the well layer of taking once or several times pressing crack construction measure is implemented fracturing reform again.As far back as the 1950's, just carried out refracturing abroad, development through more than 50 years, reservoir reevaluating, well and story selecting new technology, fracturing liquid, fractured well performance prediction, refracturing crack steering mechanism, refracturing optimal design and the aspects such as technology research, crack Diagnosis and effect assessment all are rapidly developed before refracturing, not only become the increasing yield and injection means of hydrocarbon-bearing pool, also become economical and effective and develop gordian technique hypotonic, ultra-low permeability reservoir.
Hydraulic fracturing technology is applied to the exploitation in low-permeability oil gas field, begins to have so far more than 50 year from nineteen forty-seven.Become with regard to technology that hyposmosis and extra-low permeability Reservoir Development are indispensable, ripe and effective petroleum engineering technology.
Have different hydrocarbon reservoirs in order to solve better, the oil gas field of exploitation and exploitation characteristics is at the different phase Main Problems, hydraulic fracturing technology is also constantly proposing new approaches and is developing new method.
At that time technology and level of understanding restriction just begun refracturing research abroad as far back as the sixties, owing to it is generally acknowledged that refracturing is the further extension of original hydraulic fracture or again opens closed hydraulic fracture.The mid-80, along with oil gas price changes and the development of modern hydraulic fracturing technology, abroad (mainly being the U.S.) again with refracturing as an important technical research problem, possibility, the refracturing of managing and make new seam from refracturing assessment, refracturing seam producing machine select well to comment the aspects such as a layer principle, refracturing design and construction to carry out theoretical research and field experiment analysis, make multiple fracturing technique obtain a series of major progresses.
USDOE in 1987 change the pressure break experiment of stress in many wells experiments, first proved stress field be subject to the impact of offset well crack.Dowell company is thought according to experiment and simulated ground stress research, exist supporting crack will change near the stress distribution of well in the stratum, make the crack initiation orientation of refracturing perpendicular to first crack, leave to redirect to again after the well certain limit and be parallel to first fracture azimuth and extend.Chen ﹠amp; The researchs such as Minner are thought that pore pressure changes and are caused new crack approximately perpendicular to crack last time or with last time the crack was in an acute angle.Chevron Oil Tech Inc shows in the test in U.S. Lost Hill oil field, refracturing fracture azimuth and 30 ° of first fracture orientation skews; Unocal company has confirmed that in the test of the refracturing in Van oil field the refracturing crack may depart from 60 ° with fracture azimuth last time.The development of multiple fracturing technique that these have tested the promotion strong with research has obtained extremely significant economic benefit.For example, Rangely oil field, one of oil field that the U.S. develops the earliest, many well refracturings reach 4 times, and success ratio reaches 70-80%; Refracturing is 185 mouthfuls in 385 mouthfuls of producing wells in Kuparuk River oil field, U.S. Alaska, and productivity index has on average improved twice after pressing.
A large amount of refracturing operations has also been carried out in the oil fields such as recent year grand celebration, triumph, long celebrating, huge port, Jilin, and has done certain exploration from theory and practice, has obtained some experiences and understanding.Since nineteen ninety-five, Southwest Petrol University has successively carried out STUDY ON REPETITIVE FRACTURING TECHNOLOGY with Liaohe Oil Field, long celebrating oil field, Xinjiang Oilfield and Shengli Oil Field, and with the changed course refracturing test that has launched the new seam of the stifled old seam pressure of high water-cut stage in length celebrating oil field, the Xinjiang Oilfield cooperation, obtain good effect of increasing production, opened up the new direction of refracturing research.
The process of stifled pressure integrated technique is to use first the long-acting shutoff of blocking agent or the temporary transient old crack of shutoff, and then other orientation presses off new crack on the stratum with waterfrac treatment technique, again transforms reservoir to reach, and improves the purpose of reservoir recovery.Behind the blocking agent shutoff crack, follow-up fracturing liquid must have extruding and penetration to it, therefore requires the refracturing blocking agent to have the performance higher than conventional blocking agent.
After entering old crack, refracturing blocking agent working fluid forms gel, under follow-up fracturing liquid effect, blocking agent will be subject to of the fracturing fluid extruding and penetration, therefore the performance of refracturing blocking agent will satisfy the requirement of two aspects: the one, and the strongly adherent between blocking agent-crack wall stops fracturing liquid to penetrate toward first man-made fracture; The 2nd, self has high strength blocking agent, can resist of the fracturing fluid extruding.Blocking agent not only has high intensity and adhesiveness in a word, and certain stress deformation ability will be arranged.This just requires the breakthrough pressure of blocking agent will be higher than the extruding force that is subject to.
In addition, what stifled old seam blocking agent faced is crack problem, and blocking agent also needs to satisfy leak-off low in the crack to guarantee the one-tenth colloidality matter that it is good and to reduce injury to matrix, so should take secondary to become the glue technology.Secondary becomes glue to refer to blocking agent gel a little less than ground is pre-formed lower crosslink density, claims " pregel " or a gel, after one time gel injects the stratum, again is cross-linked to form high-strength gel, i.e. two-step gelation under the reservoir temperature condition.
Thermal stability is a very important performance parameter of refracturing blocking agent, so, how to determine fast and accurately the thermal stability of refracturing blocking agent, synthetic use of refracturing blocking agent seemed most important.
Summary of the invention
The object of the invention is to overcome the shortcoming and defect of above-mentioned prior art, the method of testing of the thermal stability of refracturing blocking agent is provided, the method can test out the thermal stability of refracturing blocking agent fast, and test result is accurate, testing procedure is simple, testing cost is low, and the synthetic Data support that provides of pressure break blocking agent is provided.
Purpose of the present invention is achieved through the following technical solutions: the method for testing of the thermal stability of refracturing blocking agent may further comprise the steps:
(a) configuration refracturing blocking agent solution for standby;
(b) in refracturing blocking agent solution, add precrosslinker and promoter, and precrosslink gathered double ratio 60: 1, promoter concentration 0.01%;
(c) then be sealed in the experiment container;
(d) be positioned in the constant temperature oven;
(e) take out at regular intervals, measure its performance;
(f) analyze the thermal stability of refracturing blocking agent by data measured.
In the described step (a), the environment temperature of configuration pressure break blocking agent solution is normal temperature.
In the described step (a), by clear water configuration pressure break blocking agent solution.
In the described step (c), experiment container is the high temperature steel cylinder.
In the described step (d), the temperature of constant temperature oven is 80 ℃.
In the described step (e), be 1 hour interval time.
In sum, the invention has the beneficial effects as follows: can test out fast the thermal stability of refracturing blocking agent, and test result is accurate, testing procedure is simple, and testing cost is low, and the synthetic Data support that provides of pressure break blocking agent is provided.
Embodiment
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited only to this.
Embodiment:
The method of testing of the thermal stability of the refracturing blocking agent that the present invention relates to, its concrete steps are as follows:
(a) configuration refracturing blocking agent solution for standby;
(b) in refracturing blocking agent solution, add precrosslinker and promoter, and precrosslink gathered double ratio 60: 1, promoter concentration 0.01%;
(c) then be sealed in the experiment container;
(d) be positioned in the constant temperature oven;
(e) take out at regular intervals, measure its performance;
(f) analyze the thermal stability of refracturing blocking agent by data measured.
In the described step (a), the environment temperature of configuration pressure break blocking agent solution is normal temperature.
In the described step (a), by clear water configuration pressure break blocking agent solution.
In the described step (c), experiment container is the high temperature steel cylinder.
In the described step (d), the temperature of constant temperature oven is 80 ℃.
In the described step (e), be 1 hour interval time.
The present invention is with 2,000,000 molecular weight refracturing blocking agents, fixedly host concentration 2%, the poly-double ratio of precrosslink 60: 1, promoter concentration 0.01%, secondary cross-linking agent concentration 1.2%, observe system long-term thermal stability situation under 80 ℃ of temperature, as shown in the table by the result that said method records:
The above only is preferred embodiment of the present invention, is not the present invention is done any pro forma restriction, and every foundation technical spirit of the present invention, any simple modification, equivalent variations to above embodiment does all fall within protection scope of the present invention.
Claims (6)
1. the method for testing of the thermal stability of refracturing blocking agent is characterized in that, may further comprise the steps:
(a) configuration refracturing blocking agent solution for standby;
(b) in refracturing blocking agent solution, add precrosslinker and promoter, and precrosslink gathered double ratio 60: 1, promoter concentration 0.01%;
(c) then be sealed in the experiment container;
(d) be positioned in the constant temperature oven;
(e) take out at regular intervals, measure its performance;
(f) analyze the thermal stability of refracturing blocking agent by data measured.
2. the method for testing of the thermal stability of refracturing blocking agent according to claim 1 is characterized in that, in the described step (a), the environment temperature of configuration pressure break blocking agent solution is normal temperature.
3. the method for testing of the thermal stability of refracturing blocking agent according to claim 1 is characterized in that, in the described step (a), by clear water configuration pressure break blocking agent solution.
4. the method for testing of the thermal stability of refracturing blocking agent according to claim 1 is characterized in that, in the described step (c), experiment container is the high temperature steel cylinder.
5. the method for testing of the thermal stability of refracturing blocking agent according to claim 1 is characterized in that, in the described step (d), the temperature of constant temperature oven is 80 ℃.
6. the method for testing of the thermal stability of refracturing blocking agent according to claim 1 is characterized in that, in the described step (e), be 1 hour interval time.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104111265A (en) * | 2013-06-28 | 2014-10-22 | 成都迈斯拓新能源润滑材料有限公司 | Detection method for heat stability of organic heat carrier |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104111265A (en) * | 2013-06-28 | 2014-10-22 | 成都迈斯拓新能源润滑材料有限公司 | Detection method for heat stability of organic heat carrier |
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Application publication date: 20130417 |