International Journal of Science, Engineering and Technology Research (IJSETR) s2

International Journal of Science, Engineering and Technology Research (IJSETR) Volume 1, Issue 1, July 2012

Coagulation Treatment of Drilling Fluids from Htaukshabin-Kanni Petroleum Oil- Field using Alum and PAC

Ni Ni Myint, May Zin Lwin, Chaw Su Su Hmwe

 lignite (XP-20) to keep the mud in a fluid state, and various Abstract— This paper was studied on the coagulation additives that serve specific functions. treatment of drilling fluids from a water-based mud system of Conventionally, there were classified into three main the well (K-307) in Htaukshabin-Kanni oil-field using alum and categories of drilling fluids according to the base fluid used poly aluminum chloride (PAC). In this research, the stirred- tank reactor (STR) was used and constructed with 304- in their preparation. They are air-based, water-based and oil- stainless steel. Firstly, these were analyzed chemical based drilling fluids. Water-based drilling fluids are most compositions such as biochemical oxygen demand (BOD), used for the drilling operations of the world. About 5-10% chemical oxygen demand (COD) and pH etc. The factors (i.e. of the wells drilled use oil-based drilling fluids and a much coagulant type, chemical dosages, dilution ratio) influencing smaller percentage use air-based drilling fluids [10]. the treatment effects were investigated, and 16g of coagulant Our Myanmar has 28 onshore oil-fields [3]. Some of the per liter of waste was determined as optimal dosage for the coagulation. The practicality of using PAC rather than alum oil-fields produce large volume of by-product waste has been investigated with the dilution ratio of waste fluid to generated during drilling operations such as drilling fluids. water (1:3 and 1:5). The key advantage of PAC, which used as Environmental concerns and the prospect of beneficial uses coagulant in the chemical coagulation, is more efficient in have driven research into the treatment of drilling fluids. lower dosages of chemical and it is formed larger and more In the drilling operation, the effluent waste water freely settle-able floc than alum. The results evaluated for the considered the parameters BOD and COD for wastewater most effective sample as the percentage removal of BOD and COD with 99.7% and 99.7% respectively after coagulation. reuse. The high values of BOD, the untreated wastewater The final treated samples were characterized by chemical can cause rapid depletion of dissolved oxygen if it is directly compositions and FTIR. discharged into the surface water sources. The drilling fluids can cause serious environmental problems due to their BOD Index Terms - Alum, BOD, COD, PAC, STR. and COD. So, they have to be removed before being discharged into the environment. I. INTRODUCTION From the several methods of treatment of wastewater, Every community produces both liquid and solid wastes. "the chemical coagulation technology" was provided for the Most wastes require some type of treatment before they can experiment. Because of the nature of the colloidal be disposed of. Petroleum is a major source of energy and suspension, these particles will not sediment or be separated revenue for many countries, and its production has been with conventional physical methods (such as filtration or described as one of the most important industrial activities settling) unless they are agglomerated through coagulation in the twenty-first century. Wastes are generated from a and flocculation [11]. For the treatment of industrial variety of activities associate with petroleum production. wastewater, coagulation and flocculation process was Produced water, drilling wastes (drilling fluids), and conducted to achieve maximum removal of COD and BOD. associated wastes are the general categories [7]. The aim of this study is to evaluate the effectiveness of In the present day, drilling fluids went through major alum and PAC as coagulants in the treatment of drilling technological evolution using a simple mixture of water and fluids in different experimental conditions. The stirred-tank clays, to complex mixtures of numerous specific organic and reactor with the flat-blade disk impeller was designed for inorganic products used [4]. Drilling fluids are made up of a this experiment. base fluid (water, diesel or mineral oil, or synthetic compound), a density-increasing material usually barium II.EXPERIMENTAL METHODS sulphate (BaSO4) (barite), bentonite clay to help remove cuttings from the well and to form a filter cake on the walls A. Sample Preparation of the hole, chromelignosulphonate (Spersene) and chrome For the experiment, sample of drilling fluids were collected from Htaukshabin-Kanni Petroleum Oil-Field, Manuscript received May 29, 2014. Central Myanmar Basin (Minbu Basin), Magway Region, Ni Ni Myint, Department of Chemical Engineering, Mandalay middle Myanmar. This oil-field was established since 1978. Technological University, (e-mail: [email protected]). Mandalay, Myanmar, +959-43045110. It was producing 1300 bbl /day until now. It is one type of May Zin Lwin, Department of Chemical Engineering, Mandalay onshore oil and gas fields. The field has got a number of Technological University, Mandalay, Myanmar, +959-259034931, (e-mail: multi-reservoir field. [email protected]). Chaw Su Su Hmwe, Department of Chemical Engineering, Mandalay Due to the ‘Thixotropic’ property of the drilling fluids, Technological University, Mandalay, Myanmar,(e-mail: first of all, each sample was diluted with the water. [email protected]).

Thixotropy builds gel strength and the viscosity increases C. Stirred-tank Reactor (STR) when the fluid is stationary [4]. And the viscosity reduces, if For construction of stirred-tank reactor, the 304 stainless the fluid is pumped and forced to flow. This thixotropic steel was used to prevent corrosion [1], [9] and [6]. The property is ideal for holding cuttings in suspension during diameter and height of the reactor are 26.67cm and 60.96 period of no circulation, and for releasing cuttings when the cm which produced height to diameter ratio 2.3:1 [8]. The fluid is subjected to high shear stress. effectiveness volume of the tank is 25L. It is specially design together with flat-blade disk. Typical dimension of flat-blade disk is 1: 1/4: 1/5: 2/3 [5]. Three equal sized flat- B. Treatment with Coagulation Process blade disks are installed to get good mixing efficiency. The For the treatment of drilling fluids, dilution and chemical impeller diameter to tank diameter ratio is 0.3675 [8]. The coagulation were applied. Drilling fluids and water were distance between the first impeller and the bottom of the mixed in the stirred-tank reactor (STR) to dilute the drilling vessel and between the two impellers are 1.5 impeller fluids due to its "Thixotropic" property. Diluted sample was diameters [8]. Four equal spaced baffles are installed to adjusted pH using 0.5 N 36% hydrochloric acid solution to prevent a vortex formation which reduces the mixing reach until neutral; then 10 weight % solution of coagulant efficiency [8]. The widths of the baffles are about one tenth was added for chemical coagulation [2]. The coagulated of the tank diameter [8]. One outlet tap was built to take out solution was stirred with 348 rpm for 12 minutes. And then the treated water from the reactor after sedimentation. it was taking placed to sediment for 3days. So, the Position of the tap from the bottom of the tank is 27.94cm. coagulation was carried out at ambient temperature. After Figure 2 is the three dimensional views of the stainless sedimentation, the treated water was drained out from tap steel stirred-tank reactor (STR). and the residues were decanted into the storage tank. A schematic block diagram of the experiment is shown in Figure 1.

Drilling Fluids

Dilution with H O (Drilling fluids: water =1:3 2 and 1:5)

Adjusted pH with Add coagulant (10wt% alum or PAC) 0.05N 36%HCl solution Coagulation (a) Top view

Stirring (348rpm, 12min)

Sedimentation For 3 days

Decanting

Mud T reated water

Figure 1. Flow diagram of chemical coagulation process (b) Isometric view (south-west view)

The design of the reactor for this experiment was based on the design of the continuous stirred-tank fermenter of J.Y.Oldshue.,"Fermentation Mixing Scale-Up Techniques, Biotechnology. Biochemical Engineering. 8 (1966): 3-24. ©1966 by John Wiley & Sons, Inc., NY

(c) Front view

Figure 3. The photo of the stirred-tank reactor

(a) Top view

(d) Right side view

Figure 2. The three dimensional views of the stirred-tank Reactor

In Figure 2, (a) top view, (b) isometric (south-west) view, (c) front view and (d) right side view of the stirred- tank reactor (STR) are systematically displayed. The figures were drawn with Auto CAD (2010) software and it can be seen clearly how to situate in the experiment and can understand easily the design of the reactor. Figure 3 describes the photo of the stainless steel stirred-tank reactor. Figure 4 shows the three dimensional views of the three flat-blade disks with the axial impeller. In Figure 4, (a) top view, (b) isometric (south-west) view, (c) front view and (d) right side view can be seen. (b) Isometric view (south-west view) In Figure 5, the photo of the three flat-blade disks with the axial impeller is displayed.

Impeller

III. RESULTS AND DISCUSSION A. Chemical Analysis of Dilution and Chemical Coagulation of Drilling Fluids (DF) First of all, sample was diluted with water to break down its "Thixotropy" [4]. Diluted sample was adjusted pH to reach until neural with HCl solution. After balancing pH, coagulant was added for chemical coagulation. And it was taken 3 days for sedimentation. The results of experiment using alum and PAC as coagulants are described in Table I and Table II.

TABLE I ANALYSIS RESULTS OF THE EFFLUENT AFTER COAGULATION BY USING VARIOUS ALUM COAGULANTS Properties Sample using alum Coagulant Singa (c) Front view pore With dilution ratio With dilution ratio waste DF to H2O (1:5) DF to H2O ( 1:3) water 8 g/L 16 g/L 8 g/L 16 g/L disch arged Sample Sample Sample Sample stand A1 A2 A3 A4 ard BOD (5days) 52.6 52.6 132.8 12.6 50 (mg/L) COD (mg/L) 47.84 51.52 33.12 49.92 100 Fe 22.5 50 22.5 100 10 (mg/L) pH 5.34 4.17 5.78 3.94 6-9

TABLE II ANALYSIS RESULTS OF THE EFFLUENT AFTER COAGULATION BY USING VARIOUS PAC COAGULANTS Properties Sample using PAC Coagulant Singa pore (d) Right side view With dilution ratio With dilution ratio waste DF to H2O (1:3) DF to H2O ( 1:5) water disch Figure 4. The three dimensional views of the three flat- 8 g/L 16 g/L 8 g/L 16 g/L arged blade stand disk with the axial impeller Sample Sample Sample Sample ard P1 P2 P3 P4

BOD(5days) (mg/L) 54.6 14.8 36.2 1.6 50 COD (mg/L) 29.44 20.24 25.76 15.36 100 Fe (mg/L) 0.05 0.05 0.08 0.3 10 pH 7.65 7.19 7.53 6.95 6-9

The experiments were conducted by varying a few experimental parameters, which were two ratios of alum and PAC dosages (8 g/L and 16 g/L ) with the two varied-dilution ratios of drilling fluid to water (1:3 and 1:5) correspondingly. In order to study their effects in coagulation, they were analysed in the department of water analysis at MSTRD (Myanma Scientific and Technological Research Department). According to the data from Table I and Table II, sample P4 is one of the most effective experiments. BOD and COD were reduced significantly with pH staying nearly Figure 5. The photo of the three flat-blade disk with the axial

International Journal of Science, Engineering and Technology Research (IJSETR) Volume 1, Issue 1, July 2012 natural. BOD, COD and soluble iron as Fe are highly was assessed such as 99.73%, for both BOD and COD. The effective and their values reached under standard conditions. removal efficiencies of sample P4 are the more effective TABLE III than other samples. SOME TREATMENT EFFECT ON ALUM AND PAC WITH TWO COAGULANT DOSAGES AND THE TWO VARIED-DILUTION RATIOS Alum P AC

Items BOD(5days) (mg/L) COD(mg/L) 100.0%

Drilling Fluids 592.8 5766.4 90.0% A1 52.6 47.84 80.0% A2 52.6 51.52 y

A3 132.8 33.12 c 70.0% n e i c A4 12.6 49.92 i f

f 60.0% E

P1 54.6 29.44 l a

v 50.0% P2 14.8 20.24 o m e

P3 36.2 25.76 R 40.0% P4 1.6 15.36 30.0% Singapore wastewater 50 100 discharged standard 20.0%

Table III is the expressions of raw condition altogether 10.0% with treated states by comparing with Singapore wastewater effluent discharged standard limits. According to Table III, 0.0% BOD values for nearly all treated samples can reach its L L L L m m 8m 8m Singapore wastewater effluent discharged standard limit , 16 , 16 :3 , :5 , 1 :3 1 :5 except sample A3. Sample A3 is one of the treated samples 1 1 using alum coagulant with 8g of 10wt% coagulant solution BOD per liter of waste and dilution ratio drilling fluids to water, 1:5. COD values of the treated samples are significantly (a)Removal Efficiency of BOD decreased under Singapore wastewater effluent discharged standard limits. It can be concluded that values of BOD and COD are under the Singapore wastewater effluent Alum P AC discharged standard limits. Consequently, sample P4 is the most effective sample for this experiment. The effectiveness as removal efficiency (%Removal) 100.0% was calculated by the following formula, 90.0%

C -C 80.0% o ×100 % Removal = y C c o 70.0% n e i c i

Where, f

f 60.0% E

Co = initial contents of wastewater (mg/L) before l a

dilution and coagulation treatment. v 50.0% o

m C = final contents of wastewater (mg/L) after e

R 40.0% dilution and coagulation treatment. 30.0% TABLE IV REMOVAL EFFICIENCY OF THE TREATED SAMPLES 20.0%

TREATED SAMPLES 10.0% ITEMS A1 A2 A3 A4 P1 P2 P3 P4 0.0%

L L L L m m 91.1 91.1 77.6 97.9 90.8 97.5 93.9 99.7 8m 8m BOD , 16 , 6 :3 , :5 ,1 % % % % % % % % 1 :3 1 :5 (5DAYS) 1 1 COD 99.1 99.1 99.4 99.1 99.5 99.7 99.6 99.7 COD % % % % % % % % (b)Removal Efficiency of COD

The removal efficiencies of each sample were Figure 6. The percentage removal efficiency of BOD and estimated exactly by the corresponding equation. From COD for treated samples values of Table IV and expression of Figure 6, sample P4

The comparisons of the raw condition, the results after They represent results of raw, treated water and dilution and the chemical coagulation of drilling fluids are residual muds. The broad band the general region of 3333- shown in Table V. 3267 cm-1 was due to the hydrogen-bonded OH groups and absorbed water. The infrared spectra (FTIR) of drilling TABLE V fluids and the interpretation of the spectra are 1633.71 cm-1. THE RESULT AFTER THE DILUTION AND THE CHEMICAL The predominant absorbance peak between 2700 and 2200 COAGULATION OF DRILLING FLUIDS cm-1 was due to "ammonium" band of this region. The peak -1 Sam- between 600 and 500 cm are attributed to vibration of the Sam- ple iodo-compounds. Dilu- Dilu- ple Singa- Drill- using Proper ted ted using pore ing PAC ties Fluid Fluid alum stand- Fluid Coag (1:3) (1:5) Coagul ards ulant ant BOD

(5days) 592.8 394 32.6 12.6 1.6 50 (mg/L) COD 5766.4 1200 288 49.92 15.36 100 (mg/L) Fe 8000 375 25 100 0.3 10 (mg/L) pH 11 9.5 10.94 3.94 6.95 6-9

Table V is the best emphasising for most effluent samples of using alum and PAC coagulants which is sample A4 and P4 from the various samples of Table I and Table II. As stated by the Table III, BOD, COD and soluble iron Fe are decreased by associating of its untreated conditions and Singapore wastewater effluent discharged standard limits. It can be seen that the sampleP4 affects nearly all parameters.

B. FTIR Results of Raw, Treated Water and Residual Muds

Fourier Transform Infrared (FTIR) spectrometry has been extensively developed over the past few years and Figure 8. FTIR spectra of the treated water of sample P4 provides a number of advantages. The major chemical groups presented in drilling fluids were identified by the FTIR spectrometry shown in Figures 7, 8 and 9.

Figure 7. FTIR spectra of the drilling fluids Figure 9. FTIR spectra of the residual muds of sample P4

The removal efficiencies of most effective sample P4 for BOD, and COD were 99.7% and 99.7% respectively. It can be seen that the removal effect of sample P4 was higher removal efficiencies than sample A4 according to Figure 6. From FTIR results, water molecules are remained both in treated water and residual muds except ammonium and iodo-compounds which were including in raw wastewater. In this experiment, it can be concluded that the optimum dosage for coagulation was 16 g of PAC per litre of waste and dilution ratio of drilling fluids to water was 1:5.

ACKNOWLEDGMENT First of all, the author deeply thank to His Excellency, the Honorable Dr.Ko Ko Oo, Minister, Ministry of Science and Technology and also would like to express his great gratitude to Dr. Myint Thein. Pro-Rector, Mandalay Technological University (MTU). And my special thanks are all teachers, Department of Chemical Engineering, Mandalay Technological University (MTU), for their encouragement and sharing ideas and to all teachers and sirs whose were directly or indirectly involved in the successful completion of this experimental research. And the author also would like to express their heartfelt thanks to MSTRD Figure 10. FTIR spectra of the treated water of sample A4 (Myanma Scientific and Technological Research Department) where the raw and treated water were analyzed as chemical and physical compositions. And the author also would like to thank their sincere thanks to Department of Chemical Technological, Research Centre, Pyin Oo Lwin for FTIR for their useful comments and suggestion throughout the research.

REFERENCES

[1] Cdncache1.a.akamaihd.netwebsite. Available: http:// www. Properties of stainless steel.com (2014) [2] G. Jixiang, C. Yongjie and C. Jingjing. "Treatment of drilling wastewater from a sulfonated mud system”, China University of Petroleum (Beijing) and Springer-Verlag Berlin Heidelberg 2013 [3] U Htin Aung, "Development in Oil and Gas Sector-Update," Director, Energy Planning Department, Ministry of Energy, Myanmar (2010) [4] H. Hole, "Drilling fluids for drilling of geothermal wells," Geothermal Consultants NZ Ltd., Birkenhead, Auckland, New Zealand, June 2008. [5] J.Y. Oldshue.,"Fermentation Mixing Scale-Up Techniques, Biotech. Bioeng. 8 (1966):3-24. ©1966 by John Wiley & Sons, Inc., NY [6] B. Leffler, stainless steels and their properties. [7] J.C. Reis, "Environmental Control in Petroleum Engineering." Figure 11. FTIR spectra of the residual muds of sample A4 Gulf Publishing Company, Houston, London, Paris, Zurich, Tokyo [8] J.M.LEE, "Biochemical engineering, Prentice-Hall International Editions IV. CONCLUSION [9] Long products stainless grade sheet, North American Stainless In this study, these drilling fluids from Htaukshabin- (NAS). [10] M. A. Ekpo and V. O. Nwaugo, "Effect of Drilling Mud Kanni Petroleum Oil-Field were treated using alum and Additives on the Physiological Characteristics of Cassava Plant PAC as coagulants. First, the 304 stainless steel stirred tank Under Intercrop in the Tropics," Departments of Microbiology, reactor having volume of 25 L was constructed with three Univ of Uyo, Akwa Ibom State, Nigeria equal sixed flat-blade disk and two impellers. And the [11] M. Solanki, S. Suresh, S. N. Das and K. Shukla, "Treatment of Real Textile Wastewater using Coagulation Technology," experiments were conducted by varying coagulants dosage Department of Chemical Engineering, Maulana Azad National (8g/L and 16g/L) and dilution ratios of drilling fluids to Institute of Technology, Bhopal, India. water (1:3 and 1:5). According to the chemical analysis of the effluents after coagulation and sedimentation, both BOD and COD were reduced significantly with pH staying nearly natural BOD, COD and soluble iron as Fe are highly effective and their values reached under standard conditions.