LU501334B1 - A new hydrogen sulfide scavenger for drilling fluid and its preparation method - Google Patents

Abstract

The invention belongs to the technical field of removing hydrogen sulfide gas in drilling shaft, and discloses a new hydrogen sulfide scavenger for drilling fluid and its preparation method, and for the first time, ferrous gluconate organic compounds are used as sulfur removal reagent for drilling fluids; ferrous gluconate is a carbohydrate with high solubility, the dissolved ferrous ions react quickly with sulfur ions to form precipitate; as a carbohydrate, ferrous gluconate will not pollute the drilling fluid system and oil and gas reservoir; chemical experiment evaluation of ferrous gluconate and hydrogen sulfide gas will be used to determine the action law, the best action conditions and action mechanism of ferrous gluconate and hydrogen sulfide gas, can greatly reduce the harm concentration of hydrogen sulfide gas into the drilling shaft, reduce its corrosion to downhole drilling tools and provide theoretical basis and technical support for the exploitation of high-sulfur oil and gas reservoirs in China.

Description

A NEW HYDROGEN SULFIDE SCAVENGER FOR DRILLING FLUID AND ITS 17501384

PREPARATION METHOD FIELD OF THE INVENTION

[0001] The invention relates to the technical field of removing hydrogen sulfide gas in drilling shaft, in particular to a new hydrogen sulfide scavenger for drilling fluid and its preparation method.

BACKGROUND OF THE RELATED ART

[0002] Currently, existing technology commonly used in the industry is as following: Sulphur-bearing natural gas is abundant in China, mainly distributed in Sichuan Basin, Bohai Bay, Ordos, Tarim Basin and Zhugeer Basin. At present, the proven natural gas with high H2S content accounts for 1/4 of China's reservoir gas reserves, which is about 99 billion m3; 2/3 of the gas fields in Sichuan Basin contain H2S; H2S content In ZhaoLanzhuang sulfur gas reservoir of Huabei Oilfield is up to 92%, which is one of the world's high sulfur gas reservoirs.

[0003] In recent years, with the increasing demand for green energy in China, safe exploration and development of sulfur-containing gas fields, especially gas fields with high H2S content, has been gradually getting more and more attention. But H2S is a highly toxic gas that smells like rotten eggs. Odor concentration limit of the hydrogen sulfide that the human body can smell is 28mg/m3, when the concentration in the air exceeds this value, people cannot work normally; more than 1000mg/m3, it will cause acute poisoning, and people will lose reason and balance perception, resulting in breathing difficulties; smelling for 2-15 minutes, people will stop breathing, if not be timely rescued, one will be poisoned to death; In 2003, drilling the Luojia 16H well resulted in a high concentration of sulfurous gas spewing to the surface, resulting in more than 200 deaths and injuries, making it the worst drilling accident in China's drilling history. When H2S gas is dissolved in water-based drilling fluid, the pH of the system will be reduced and the rheological property of the drilling fluid will be affected. At the same time, free hydrogen ions will erode into the interior of drilling tools, causing stress corrosion, resulting in hydrogen embrittlement (intergranular corrosion and transgranular corrosion) of drilling tools, and even fracture, resulting in serious downhole complex accidents. Under the condition of high H2S concentration 1 and high drill stress, the downhole accident of drill string fracture may occur in a few LU501334 minutes. Relevant data show that there are about 500 drilling accidents in China National Petroleum Corporation every year in recent years, and the accidents caused by corrosion account for 75% to 85%. Therefore, in the process of drilling, it is an important economic and technical problem to prevent the corrosion of drilling tools and ensure the underground safety. How to safely and efficiently prevent the drilling tools in drilling shaft from corrosion of dissolved H2S and protect the life safety of ground staff is inevitable and has become the urgent matter for exploration and development of oil and gas reservoirs with H2S, and should be paid great attention to. At present, when drilling sulfur gas reservoirs, increasing the density of drilling fluid relied on to increase the pressure of drilling fluid column is often applied, in order to prevent H2S gas from entering the drilling shaft, prevent it from flowing up to the surface; increasing the pH value of the drilling fluid system to neutralize dissolved H+; even add basic chemical reagents such as sponge iron or basic zinc carbonate to the drilling fluid system to react with dissolved H2S gas and reduce its hazardous concentration. However, these technical measures have certain limitations, which may lead to other technical difficulties.

[0004] 1) Increasing drillig nfluid density will pollute oil and gas reservoirs. When drilling reservoirs containing H2S, increasing drilling fluid density is usually used to completely crush H2S gas reservoirs; however, due to the high density of drilling fluid, the pressure of drilling fluid column is greater than the pressure of oil and gas reservoir, the solid particles in the drilling fluid system enter the oil and gas reservoir under the action of pressure difference, blocking the cracks or pore passage in the oil and gas reservoir, reducing the permeability of oil and gas reservoir, and ultimately affect the recovery of natural gas. Therefore, considering the problem of reservoir protection, only relying on the technical measures of increasing drilling fluid density has certain limitations.

[0005] 2) Increase the pH value of drilling fluid will increase the drilling cost; During the exploitation of sulfur-bearing reservoirs, at home and abroad, alkaline materials are often added to drilling fluid system to improve the pH value of drilling fluid system to slow down the corrosion of acid ions; Increase the pH value of water-based drilling fluid to more than 10 (that is, increase the alkalinity of the drilling fluid), so that it can produce acid-base neutralization reaction with dissolved hydrogen sulfide gas, so that H2S can be converted into sulfide ion form, and inhibit the generation of H2S containing covalent 2 ions; the concentration of H2S gas containing covalent ions in the drilling fluid LY501334 decreases, and the gas vapor pressure will decrease, so the release of hydrogen sulfide gas is no longer significant. When drilling high- sulfur oil and gas reservoirs, a large number of H2S gas pour into the wellbore, and the dissolved hydrogen sulfide gas is neutralized by adding alkaline substances, and alkaline materials need to be continuously added to maintain the pH value required by the drilling fluid system, which inevitably increases the drilling cost; At the same time, too much alkaline material in the drilling fluid system will change the rheological properties of the system and reduce the efficiency of the drilling fluid system.

[0006] 3) Common sulfur removal reagent is insufficient to remove hydrogen sulfide gas, When drilling sulfur-bearing reservoirs, in addition to increasing the density of drilling fluid to press oil and gas layers and increasing the pH value of drilling fluid system to mitigate the corrosion of acid ions, chemicals are often added to the drilling fluid system (sulfur removal reagent), making it to react chemically with dissolved sulfur ions to form precipitate and to be removed.

[0007] At present, the chemical agents commonly used to remove hydrogen sulfide at home and abroad mainly include sponge iron, basic zinc carbonate and zinc compounds.

[0008] 1) Sponge iron is a kind of high porosity non-magnetic synthetic iron oxide solid material, mainly composed of ferric oxide, almost insoluble; the sulfur ions in the drilling fluid system shall react with it to generate FeS precipitation, which shall diffuse to the surface and penetrate into the sponge iron, and the reaction process shall take a certain time; When drilling a high-sulfur oil and gas reservoir, a large amount of H2S gas enters the drilling shaft, and the sponge iron has no time to react with it, and most of the hydrogen sulfide gas or dissolved sulfur ions return to the surface with the circulation of drilling fluid, posing a threat to the life and safety of surface workers.

[0009] 2) Basic zinc carbonate and zinc compounds have a certain solubility, which is better than sponge iron in removing hydrogen sulfide gas; However, zinc is not easy to degrade and will seriously pollute the formation environment; In addition, zinc substances will change the rheological properties of water-based drilling fluid system, leading to the flocculation of the drilling fluid system; in the drilling process, if the rheological parameters of drilling fluid are not well controlled, the rock-carrying capacity of drilling fluid system will decrease, resulting in drilling accidents such as sand sinking and sticking. In the process of drilling, hydrogen sulfide will invade into drilling fluid of 3 drilling shaft to varying degrees when drilling in sulfur-bearing formation, which greatly LJS01334 endangers personal safety, and causes hydrogen embrittlement corrosion of drilling tools and well control devices, causing fracture of drilling tools and damage of wellhead equipment, and bringing great hidden dangers to well control work, and even causing blowout; and the performance of drilling fluid will be deteriorated sharply, in serious cases, the drilling fluid can form frozen jelly and lose its fluidity. In order to drill safely and efficiently, it is necessary to remove hydrogen sulfide that invades into the drilling fluid in time. Therefore, itis of great significance for to create a highly efficient chemical sulfur remover with good cleaning effect, no negative impact on drilling fluid performance and no pollution of formation environment, to deal with hydrogen sulfide in drilling fluid invading drilling shaft.

[0010] When drilling in sulfur-containing oil and gas reservoirs, the main technologies to control hydrogen sulfide at home and abroad include increasing drilling fluid density, keeping drilling fluid highly alkaline, using chemical sulfur removal agents, etc. by increasing drilling fluid density, and increasing pressure of drilling shaft liquid column, making it greater than the pressure of ground layer, this way is reliable, but in the target layer when drilling, drilling shaft fluid column pressure is greater than the formation pressure, the solid phase particles in drilling fluid can get inside the reservoir under the action of pressure difference, plugging or filling cracks or porosity in the reservoir, reducing the permeability of reservoir, therefore, improving the density of drilling fluid has some limitations in practical applications. By increasing the pH value of water- based drilling fluid to more than 10, it can react with hydrogen sulfide in an acid-base neutralization reaction, in this way, free H2S can be converted to sulphide ion form, inhibiting the production of H2S containing covalent ions; when the concentration of H2S containing covalent ions in drilling fluid decreases, the vapor pressure of gas will decrease, and the release degree of hydrogen sulfide gas will decrease, however, due to the limited absorption capacity of drilling fluid system, the amount of H2S in oil and gas reservoirs cannot be accurately predicted, and a large amount of unknown H2S gas cannot be absorbed by simply increasing the alkalinity of drilling fluid, once the pH value of the drilling fluid decreases, the generated sulfide will be converted to hydrogen sulfide gas again, high pH value will seriously affect performance of the drilling fluid. Therefore, the method of increasing pH value cannot completely solve the harm of hydrogen sulfide. 4

[0011] Therefore, gradually more reliable sulfur removal measures at home and abroad LV501334 is to selectively add a metal compound - sulfur removal agent, so that it can react with hydrogen sulfide, producing sulfide precipitation to remove sulfide in drilling fluid. At present, the main sulfur removal agents used at home and abroad include sponge iron, basic zinc carbonate and zinc chelate, and a great deal of work has been done in basic zinc carbonate: Basic zinc carbonate is a complex compound that contains zinc hydroxide, 1 Ib/ bbl (about2 .853kg/m3) of basic zinc carbonate removes approximately 1500mg/l of sulfur, although this scavenger has a high zinc content, it contains 2% by weight carbonate (CO32-), hence will slightly flocculate the treated drilling fluid with a high solid content, so lime must be added to precipitate it; for the pretreatment of water- based drilling fluid systems, the use of this agent should be limited to less than 2lb/ bbl, and in drilling fluid, Zn2+ will displace sodium ions in bentonite, affecting the thickness of the double electric layer, resulting in the increase of the volume of bentonite, resulting in fluid loss and deterioration of rheological properties; another disadvantage is that zinc is a non-degradable heavy metal pollutant with potential environmental impact, in the sulfur removal test of drilling fluid, both the reaction products and unreacted parts with sulfide will be separated by the solid phase control equipment and drilling cuttings, or remain in the drilling fluid, waste components eventually end up at sea or on land for disposal, potentially poisoning some plants, and potentially carrying the heavy metal load into liquids that seep out of the soil, affecting groundwater and surface water. Therefore, the presence of zinc indicates a potential serious pollution.

[0012] Sponge iron is the earliest sulfur removing reagent used in drilling fluid at home and abroad; as it is a solid substance, it is almost insoluble; hydrogen sulfide reacts very quickly with surface solid particles, removing 30% of the hydrogen sulfide gas by volume during the initial immersion of hydrogen sulfide into the drilling shaft, but it takes a long time for the sulfur to diffuse into the solid, the slow diffusion of sulfur ions into the sponge iron limits the overall reaction speed and degree, and the reaction efficiency between them is best when the pH value is less than 8, while the pH value of drilling fluid system is generally in the range of 8 to 10, this reflects the one-sided removal of hydrogen sulfide by sponge iron in the borehole, resulting in an unsatisfactory effect. In 2008, Tabei Mud Material Co., Ltd. developed a new inorganic compound sulfur removal material, which is a compound in addition to zinc, mainly containing calcite, calcium hydroxide, quartz, zinc, kaolinite, sodium montmorillonite; under downhole 5 conditions of high temperature and high pressure, H2S invading to the drilling fluid LY501384 dissolves and forms vulcanized silicone rubber with silicon, removing part of the sulfide. However, they are all solid phase substances with high solubility: after adding a certain amount, the density of drilling fluid increases and the solid phase content of drilling fluid increases, which will eventually affect the rheological properties of drilling fluid. In 2009, a drilling fluid company in Guanghan, Sichuan province, produced a new zinc-rich compound, a kind of compound, mainly contains calcite, kaolinite, magnesite, and some quartz and illite; the substances acting with sulfide are not only zinc ions, but also calcium ions, silicon materials and magnesium; magnesium will neutralize some sulfur ions, and silicon materials will generate a small amount of sulfide silicone rubber with sulfide under the conditions of underground high temperature and high pressure, and remove some sulfur ions; calcium and hydrogen sulfide will generate CaS precipitates, but CaS will be rapidly decomposed by acid to release H2S, therefore, when using this compound sulfur removing agent, it is necessary to keep the pH value of drilling fluid large enough to avoid a large amount of H2S gas intrusion into the well and seriously reduce the pH value of drilling fluid, so that the CaS precipitates will re-release hydrogen sulfide gas.

[0013] In recent years, in addition to the development of various inorganic compound sulfur removal reagent, high solubility (approximate liquid state) sulfur removal substances have been gradually developed: such as the new nitrate nitrite: it mainly depends on increasing the solubility of sulfur removal reagent, shortening the reaction time of metal ions and H2S gas, to achieve the purpose of rapid removal of hydrogen sulfide; in recent years, domestic research in this field has been limited-- there is no other perfect sulfur removal technology for drilling fluid except zinc compound sulfur removal reagent. The sulfur remover used in drilling fluid in China is mainly inorganic, with little varieties and functions. In the future, the research work on sulfur remover will develop towards the combination of inorganic and organic compounds and the combination of liquid organic sulfur remover ion chelate and high solubility organic material. In the process of increasing and expanding oil and gas exploration and development, it is inevitable to drill more and more hydrogen sulfide oil and gas reservoirs, and the safety exploration and development of hydrogen sulfide oil and gas reservoirs is imminent; it is necessary to study how to prevent the drilling tools in drilling shaft and life and property of ground personnel safely and efficiently from corrosion of hydrogen sulfide, and it has become an urgent matter for exploration and development 6 of hydrogen sulfide reservoirs. Hydrogen sulfide gas is hazardous, with severe toxicity, L/501334 when being exposure to the concentration of 200ppm in the air, one's olfactory system will be immediately destroyed; eyes, throat will has feeling of burning; when being exposure to it for a long time, one's eyes, throat and fatal will be burned; If it reaches 500ppm, people will lose their sense of reason and balance, and have difficulty breathing; when being exposure to it for 2-15 minutes, one will stop breathing , and die from poisoning if not rescued in time. In addition, H2S gas dissolved in water-based drilling fluid is highly corrosive; In the process of oil and gas exploitation, serious corrosion damage will occur due to the presence of hydrogen sulfide gas, which can lead to the release of tubing, dense corrosion holes, and loss of control of valve corrosion, resulting in the early abandonment of oil well pipe and affecting normal production, it will even cause explosion, combustion and other sudden disaster accidents.

[0014] To sum up, the problems existing in the prior art are:

[0015] In recent years, a variety of inorganic compound sulfur removal reagents have been developed abroad, but the efficiency of removing hydrogen sulfide gas is not high, and the amount consumed in drilling operations is large, which will inevitably increase the drilling cost; in addition, zinc-based drilling fluids with sulfur removal substances will also cause drilling fluid flocculation, changing the rheological properties of drilling fluids, and seriously causing the abandonment of wellbore drilling fluids; at the same time, zinc-based drilling sulfur removal substances are bound to have zinc ions, which will pollute the environment. Therefore, foreign countries have been gradually doing research of high solubility sulfur removal material, domestically, in addition to the development of zinc compound sulfur removal reagent, there is no other more perfect drilling fluid sulfur removal technology, with little varieties and functions. The new hydrogen sulfide scavenger for drilling fluid has a very high solubility, and dissolved sulfur ions can quickly react to generate precipitation to react off a large number of hydrogen sulfide gas, and sulfur removal efficiency is very high; at the same time, the reagent is organic and will not contaminate the formation near the drilling shaft.

SUMMARY OF THE INVENTION

[0016] Aiming at the problems existing in the prior art, the invention provides a new hydrogen sulfide scavenger for drilling fluid and its preparation method.

7

[0017] The invention shall be realized in the following ways: a new hydrogen sulfide LV501334 scavenger for drilling fluid, mainly contains C, H, O and Fe elements, chemical formula is C12H22FeO14; it consists of gray or light yellowish green fine powder or particles, with a caramel smell, and high solubility; 1g sample under the condition of slight heating will be soluble in 10mL of water, and insoluble in alcohol.

[0018] The invention also aims to provide a new hydrogen sulfide scavenger for drilling fluid, including the following steps:

[0019] Step 1, dissolve CgH1107 in water to obtain CeH11O7 and Ca?*. Add H2SO4 solution to the above mixed solution and heat it to 90°C to obtain CeH1207CaSO4 precipitation;

[0020] Step 2, the solution of CeH1207CaSO4 shall be separated to obtain CaSO4 and CsH1207, and then, use CeH1207 to obtain CeH1207 by column chromatography;

[0021] Step 3, dissolve Na2CO»s in water to obtain Na* and CO37 solutions; the solution of Fe?* and SO«4? shall be obtained by adding FeSO4 to water; mix the solution containing Na and *COs? with the solution containing Fe?* and SO4*, to obtain FeCO3 precipitate, Na:SO4 solution, the NazSO4 solution shall be separated and the FeCO3 precipitate shall be washed with water to obtain pure FeCOs precipitate;

[0022] Step 4, FeCOs3 precipitation and the above obtained CeH1207 shall be reacted to obtain (CsH1207)2Fe solution, and the obtained solution shall be crystallized and dried to obtain the product.

[0023] In conclusion, the advantages and positive effects of the invention are as follows:

[0024] The new hydrogen sulfide scavenger for drilling fluid has a very high solubility, and dissolved sulfur ions can quickly react to generate precipitation to react off a large number of hydrogen sulfide gas, and sulfur removal efficiency is very high; at the same time, the reagent is organic and will not contaminate the formation near the drilling shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG 1 is a flow chart of preparation method of the new hydrogen sulfide scavenger for drilling fluid provided by embodiment of the invention.

[0026] FIG. 2 is a schematic diagram of a sulfur removal tester at room temperature and pressure provided by embodiment of the invention. 8

[0027] FIG. 3 is a schematic diagram of the best sulfur removal effect comparison of LV501354 various sulfur removal agents provided by embodiments of the invention.

[0028] FIG. 4 is a schematic diagram of the molecular structure of ferrous gluconate provided by an embodiment of the invention.

[0029] In the figure: 1. H2S standard gas; 2. valve; 3. flow meter; 4. glass sieve plate absorption bottle; 5. test sample (50ml); 6. glass tube connected with acid resistant H2S corrosion connector; 7. rubber plug; 8. glass sieve plate with good ventilation; 9. H2S; 10. PGM-50Q detector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention will be further described in detail in combination with embodiments as follows. It should be understood that embodiments described herein are intended only to explain and not to qualify the invention.

[0031] The invention can greatly reduce the harmful concentration of hydrogen sulfide gas invading drilling shaft, reducing its corrosion to downhole drilling tools, and providing technical support and safety guarantee for the exploitation of high-sulfur oil and gas reservoirs in China.

[0032] The following is a detailed description of the application principle of the invention combined with the attached drawings.

[0033] Ferrous gluconate is used in the new hydrogen sulfide scavenger for drilling fluid provided in an embodiment of the invention.

[0034] The novel hydrogen sulfide scavenger for drilling fluid, contains C, H, O and Fe elements, chemical formula is C12H22FeO14; it consists of gray or light yellowish green fine powder or particles, with a caramel smell, and high solubility; 1g sample under the condition of slight heating will be soluble in 10mL of water, and insoluble in alcohol.

[0035] As shown in FIG 1, the preparation method of the novel hydrogen sulfide scavenger for drilling fluid provided in an embodiment of the invention includes the following steps:

[0036] S101: dissolve CsH1107 in water to obtain CeH1107 and Ca?*. Add H2SO4 solution to the above mixed solution and heat it to 90°C to obtain CeH1207CaSO4 precipitation; 9

[0037] S102: the solution of CeH1207CaSO4 shall be separated to obtain CaSO4 and LY501354 CsH1207, and then, use CeH1207 to obtain CeH1207 by column chromatography;

[0038] S103: dissolve Na2COs3 in water to obtain Nat and COs? solutions; the solution of Fe?* and SO«4? shall be obtained by adding FeSO4 to water; mix the solution containing Na and *COz* with the solution containing Fe** and S042, to obtain FeCO3 precipitate, Na:SO4 solution, the NazSO4 solution shall be separated and the FeCO3 precipitate shall be washed with water to obtain pure FeCOs precipitate;

[0039] S104, FeCO3 precipitation and the above obtained CsH1207 shall be reacted to obtain (CsH1207)2Fe solution, and the obtained solution shall be crystallized and dried to obtain the product.

[0040] The following is a detailed description of the application effect of the invention combined with experiments.

[0041] An experimental apparatus for the reaction of ferrous gluconate with hydrogen sulfide shall be established; A certain concentration of hydrogen sulfide standard shall pass through a absorption bottle with a certain amount of sulfur removal reagent, and by detecting the concentration of hydrogen sulfide at the outlet, the amount of hydrogen sulfide gas reflected by the addition of ferrous gluconate could be judged. During the experiment, different hydrogen sulfide standard gas can be used for evaluation, also, the amounts of ferrous gluconate can be changed, and the pH value of the liquid in the absorption bottle can be changed. It can be tested and evaluated by many experiments to establish the best working conditions of sulfur removal reagent such as ferrous gluconate and judge the removal effect of sulfur removal reagent. According to the same method, the cleaning effect of sulfur removing reagent and hydrogen sulfide used in drilling fluid and the best working conditions shall be tested, and the cleaning effect shall be compared with that of ferrous gluconate.

[0042] In order to verify the effect of the two synthetic organic desulfurizer on removing hydrogen sulfide, it shall be compared with basic zinc carbonate, sponge iron, inorganic compound desulfurizer B and inorganic compound desulfurizer A produced in China; the experiment was carried out in China National Environmental Protection Product Quality Supervision and Inspection Center under normal temperature and pressure.

[0043] 1. Experimental instruments 10

[0044] The experimental apparatus shall be assembled as shown in FIG. 2: connect LV501354 the glassware to the instrument and place it in the fume hood with the air volume adjusted to the maximum; place the hydrogen sulfide standard cylinder outside the fume hood and connect it to the test instrument.

[0045] 2. Experimental methods

[0046] The test environment shall be room temperature, standard atmospheric pressure (100.6KPa); the inlet concentration (standard gas concentration, 10-6L/L) shall be 998ppm, and the flow rate is 120L/H, and pass through the drilling fluid with 1% ferrous gluconate , the outlet hydrogen sulfide concentration shall be detected after reaction. Drilling fluid formulation: 1% bentonite + 0.1% caustic soda + 0.3% CX- 215+ 0.3% DRISPAC+ 1.2% JMP+ 1.0% PF-PRD+ 1.75% YX-1+ 1.25% YX-2+ limestone powder.

[0047] 3. Experimental procedures

[0048] Take the glass sieve plate shown in FIG. 2 out of the absorption bottle, and use the measuring cylinder to take 50mL drilling fluid sample with ferrous gluconate and pour it into the absorption bottle; insert the glass tube with a glass sieve plate and another glass tube into the rubber plug, and then into the absorption bottle, cover the rubber plug tightly, so that the sieve plate is 3mm away from the bottom of the absorption bottle; open the H2S standard gas cylinder, and adjust the pressure reducing valve, and adjust the H2S gas flow to 120L/H, and start the stopwatch. Use PGM250Q detector to measure H2S gas concentration C2 per minute from the outlet of absorption bottle with glass sieve plate until C2 reaches or approaches the upper limit of measurement range of PGM250Q detector.

[0049] The calculation formula of H2S gas removal efficiency is as follows:

[0050] G= (C1-C2)/C1 x100%

[0050] G= (C1-C2)/C1 x100%

[0051] In the formula, G is the removal efficiency of hydrogen sulfide gas of the sample, % (V/V), C1 and C2 are the concentration of hydrogen sulfide gas at the inlet and outlet respectively, 1x10-6L/L.

[0052] 4. Experimental results

[0053] The best removal data of organic sulfur removing reagent, basic zinc carbonate, sponge iron, inorganic compound sulfur removing agent -B and inorganic compound sulfur removing agent -A are compared as follow. 11

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EEE Testtimes | : ; aT AN Ÿ Ÿ = $ esttirmes- i i 3 Ÿ 3 $ . $ 3 3 x x 3 . 3 3 3 3 3 Ë i x ï x i i i à 3 ¥ © a A = 3 x a x N x X Pa + x 3 3 futur OÙ A Ÿ = Ÿ % © 3 $ : 3 = 3 3 Stan S „ + ; : 3 3 3 i ; PEERS à Ÿ Ÿ 5 3 = ¥ 3 3 & i = i ck : \ | 108108 1 7 0 5 A AAA i 3 $ 3 § i © © x X 3 x x inne § EEE cae | | : : : | Kae. i Ÿ Ÿ 3 ; somtimes | x ï Ÿ © i 3 3 3 5 - 33 È de 3 . 3 $ 3 3 i = i tt € ü 3 Ë © x € x i à i ary | i { Ë Ë { § 3 3 % à + à x + > © © X N Ë SE à 3 $ $ i $ 3 i s 3 SS à J 3 + = = x X 3 x Ne x EN NN 3 3 3 $ 3 ; i ADRIAN Ÿ 3 3 3 à 3 Ï D A AANA RN i i i i — x EEN 3 3 Testi È i $ S ÉTÉ 3 185-2. i § 3 Ÿ i EE SUES Sih SN Ÿ , Ÿ = ; oe 201$ 5 a 1 dx à ; i i i i find | = i ES i § 3 ES Ÿ vg i > à i N i EET EES Ÿ x A 3 = Ra N À 3 & N - aE Ë i 1 16 1 EE id 1 is 1 A i i Ÿ 3 3 7 3 : 3 a i IX sos è Ÿ © Ÿ 3 § i = NN 3 © $ 3 3 i Ÿ 3 sessions ess 3, i i i x ES On . ï i Ÿ = AS à Calor Ï i i 3 $ AAA AAAS —— . ï È Ÿ = X N > PE ESICÉENSISIE $ i x Ÿ 3 ¥ i i i a FEAST AT Ï 3. È 28 Ÿ ay = © ¥ $ 3 3 ray. 8 # § & $ 3 i $ i se $ i 3 7 t È 32 3 $ 3 x 3 i) 3 À 3 : i È Ÿ : 3 ++ Ÿ $ i N > 3 § 3 3 NE { ; { © 8 3 à | 68 1 ah — À { $ i i i 3 £5 i HH SUEUR. ¥ 3 i i Ÿ EE x Ï Ÿ Ÿ N KEN 3 3 . $ i $ S 3 Re i Te tte. i 3 3 î 3 + ee Se Î } = i o Ÿ su 3 i 3 § 3 ; $ ï s 3 sx © aix $ 3 3 i eed ; i iS i © x 3 3 i i Soba} 28 Ÿ x Ÿ M 5 SET N = 3 2 3 ç 3 min | i EX $ US © A 2 | RE 1 PM | ey 5 : i È Ÿ = PRESS ¥ x 3 aa 3 2% 3 3 ï Ÿ Ÿ = Ÿ 3 RS 3 Se 3 Sa È Ÿ = $ 3 3 st 3 cr ) > 3 3 3 3 i ss EE = ¥ i 3 i SS SS * i i ï N SR 5 Du i x Ÿ > QT Dexlet N Ÿ 3 Ë ÿ NAN et È Ë 3 £ i 3 ? A EE EATS conceztration » | + i x Ÿ i i 3 i i ~ - Ÿ 3 È S Ÿ SE $ = RSL i 5 Ë J Ÿ TR Ÿ NE i + à 3 à à AY is È 2 i So} Ÿ ES © Six 3 SE 3 a 3 © 3 i È 3 Lu X RE 3 SE À 3% i 3 } à AR ï È Ÿ = 3 3 <a 3 x 3 = x JF È Ÿ Ÿ 3 3 3 oo 3 Te RRs Ÿ X 3 3 3 3 T RA AR ARR = 3 3 3 $ RRR RAR RRR 3 3 3 3 N + EE EEE CE ECS EE CES = 3 3 _ ald È 3 = RR RRR 3 3 Tat me. i $ Ë 3 3 REN N È N Ÿ © Ÿ = 3 3 Fa à ME 3 IE © © 3 $ 3 X Si A SA = EER 3 Ny X NE X cri 3 3 3 Fiat OÙ Ae? i id Ÿ SF Ë SE $ A 3 i â EIRE OÙ Ë Ÿ be À © wed 3 = 3 SE 3 i SEE EE i $ Ë 3 dae 3 vid à save À È Ÿ = 3 $ of AS 3 i nnn 2 x 3 3 â J : 3 3 A È £ $ & à à Outlet È i } © $ : anemia È Ÿ © 3 3 TORCEITAUNE : = 5 ws Ÿ = 3 à 3 3 ART 7 4 A 3 29 Ë ; 3 3 3 X CSL; | + i 50 8 AR O5 CT 5 sa à x 3 A Ÿ a ASS = $ $ SR ENE i 1 VS ESS à 81 8 i $ Ë 4 3 33 $ Far 3 cc 3 coe = Ÿ = > X X X 3 X x X X X m x X X = N 3 3 3 3 j 3 i

[0064] Tabl

[0065] LU501334 Teme dnb pon 0 8 1 as ae vis | 601 7 & U 98 68% #8 ON

[0066] The data in Table 1-Table 6 above will be plotted in the same coordinate graph (Figure 3) to observe the best effect of various sulfur removers.

[0067] FIG 3 shows the sulfur removal effect comparison of organic sulfur removal reagent, basic zinc carbonate, sponge iron, inorganic compound sulfur removal agent -B and inorganic compound sulfur removal agent - A under their respective best sulfur removal conditions; the addition of sulfur remover is 1% of drilling fluid, and the experimental inlet concentration of hydrogen sulfide is 1998ppm. It is obvious from FIG 4that sponge iron has the worst sulfur removal effect; the experimental curves of basic zinc carbonate and compound sulfur-removing agent A are close, and the sulfur- removing effect is similar; the sulfur removal effect of compound desulfurizer -B is better than that of basic zinc carbonate and compound desulfurizer -a in the first 10 minutes, but the sulfur removal effect is close to that of the other two after 15 minutes of hydrogen sulfide penetration. The organic sulfur remover invented has the best sulfur removal effect.

[0068] Main mechanism: organic sulfur removal agent (ferrous gluconate) is a carbohydrate substance, solubility is large; dissolved ferrous ions will quickly react with sulfur glaze to produce precipitate; ferrous gluconate, as a carbohydrate, will not 14 pollute the drilling fluid system and oil and gas reservoir; using ferrous gluconate, a LV501334 new efficient and environmentally friendly sulfur removal drilling fluid technology is established, which can greatly reduce the harmful concentration of hydrogen sulfide gas entering drilling shaft, reducing its corrosion to downhole drilling tools, and provide technical support and safety guarantee for the exploitation of high-sulfur oil and gas reservoirs in China.

[0069] The above mentioned are only better embodiments of the invention and shall not be used to limit the invention; any modification, equivalent substitution and improvement made in the spirit and principle of the invention shall be included in the scope of protection of the invention.

Claims (2)

CLAIMS LU501334

1. A novel hydrogen sulfide scavenger for drilling fluid is characterized in that, the novel hydrogen sulfide scavenger for drilling fluid, contains C, H, O and Fe elements, chemical formula is C12H22FeO14; it consists of gray or light yellowish green fine powder or particles, with a caramel smell, and high solubility; 1g sample under the condition of slight heating will be soluble in 10mL of water, and insoluble in alcohol.

2. A novel hydrogen sulfide scavenger for drilling fluid according to claim 1 is characterized in that, the novel hydrogen sulfide scavenger for drilling fluid synthesis method includes the following process: Step 1: dissolve CeH1107 in water to obtain C¢H1107 and Ca?*. Add H2SO4 solution to the above mixed solution and heat it to 90°C to obtain CeH1207CaSO4 precipitation; Step 2: the solution of CeH1207CaSO4 shall be separated to obtain CaSO4 and CsH1207, and then, use CeH1207 to obtain CeH1207 by column chromatography; Step 3: dissolve Na2zCOs in water to obtain Na* and CO3% solutions; the solution of Fe** and SO4% shall be obtained by adding FeSO4 to water; mix the solution containing Na and *CO3% with the solution containing Fe?* and SO4*, to obtain FeCO3 precipitate, Na:SO4 solution, the NazSO4 solution shall be separated and the FeCO3 precipitate shall be washed with water to obtain pure FeCOs precipitate; Step 4: FeCOs precipitation and the above obtained CsH1207 shall be reacted to obtain (CeH1207)zFe solution, and the obtained solution shall be crystallized and dried to obtain the product.

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