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An investigation on chemical formation damage in Iranian reservoir by focus on mineralogy role in shale swelling potential in Pabdeh and Gurpi formations.

INTRODUCTION

Problems resulting from instability of Shale formations of oil and gas fields make well tight, pipes cased and also make formation eradication, mud loss, well deviation and other problems which explicitly and implicitly have effects on increasing drilling expenditure in addition, Clay minerals swelling near the wellbore make producing chemicals closed and formation destroyed. These dements have forced investigation to design appropriate fluid formulation for drilling and or transfusion in Shale layers which can minimize the damage to environment. In this fluid, preventing features of Shale be taken into account in order to minimize the costs resulted from above elements. Providing this fluid and it's remedy opposed a lot of costs. So, detecting Shale layers and active Clay minerals type in it necessary. The aim of this study is to determine and investigate Asmari , Pabdeh and Gurpi formations Clay minerals in oil field of Ahwaz and Maroon in order to predict and solve problems come from emerging special Clay components and reducing costs of drilling processes by optimizing drilling fluid conditions. Moreover, these result can be useful in investigating formation damages in water injection in increasing yield process. Damages depend on rock characteristics and one created because of Clay swelling in hole and also particle spreading which don't have swelling feature, during fluid process. Clay minerals in facing water are active (absorbing water and swelling potential) and inactive, Shales often have inactive Clay minerals such as Kaolinite, Illite and active minerals such as Montmorilonite. In this study by using two methods, wireline well log and XRD, active Clay minerals are determined.

Literature background:

Having clay minerals during different processes, can cause reduction in permeability of reservoir rock. this phenomena are such as Clay swelling, Clay Flocculation, formation dissolution and chemical materials absorption. Gray and Rex studied acerate Micas, Illite and Kaolinite migration. They found that migration taken place when salts density or bipolar ions density reduce or are replaced by one polar ions [1]. The process of particle migration in porous media was studied by Muecke [2]. He concluded that sand of non-solided rock, have large amounts of solid particles which are completely instate in porous media. He also recognized that fluid systems which are designed by that particles to prevent formation damage should involve not only Clay mineral but also ability to face other mineral materials problems and also non mineral materials. When fluid flow in monophase, and it has enough velocity to keep particles hanging, particles in formation move within porous media; unless they are kept by closed paths of porous media network. Created bridges in bottleneck maybe destroyed by pressure disorders or fluid return flows, when fluid flow is multi-phase, wettability and surface forces of rock and fluid, have an important effect on particles moves. Chang and Civan was studied practical model for chemically induced formation damage [3]. Civan was also studied about formation damage mechanisms and their phenomenological modeling [4]. He was also studied interpretation and correlations of clay swelling measurements [5].

Location of Ahwaz and Maroon field:

Ahwaz and Maroon oil fields are Along the Zagros zone and the largest oil fields in Dezful area are like sinus anticlinal with NW_SE rate which are located in Khuzestan, iran. Pabdeh formation with Shale lithology and Shale limes and Gurpi formation with combination of lime and Clay limes, are Such as most challenging formations drilled in these fields to access Bangestan and Khami group reservoirs. Asmari reservoir in Ahwaz oil field has Shale Sand rock lithology.

Clay swelling:

Clay swelling phenomenon takes place in reservoirs which reservoir rock has large amount of Clay minerals [1]. Water phase of drilling fluid contact or injected water with formation and absorbing water by Clays and their swelling make fluid passing entries closed [3-5]. The most important Clay minerals types in premeability reduction study for almost all sand rock reservoirs are Kaolinite, Montmorillonite, Illite, chlorite and combined mineral [5]. Clay particles swelling whose main part is Montmorillonite create instability problems of wellbore in drilling process and also there main problems in production process and EOR that are:

1) severe reduction of permeability in porous media.

2) gelatinous particles migration which cause blockage.

3) accumulation and trapping of large amounts of fluids which are shown in petrophysical logs a high percentage of water saturation. This causes the well assumed to be left, which it can produce oil without water (the known characteristics of Ahwaz Sandstone reservoir). Montmorillonite to Clay particles tend to participate in Sand formations with lower depth. Clays reactive to mentioned type don't exist in Limestone and Dolomite formations.

Methods:

1. Application of well logging data:

In oil industry different logs are used. The best one to identify shale layers is radioactive logs. Atoms nucleus radioactive elements such as Potassium, Thorium and Uranium are accumulated in Clay minerals. So, it make this log on the most appropriate log to detect Shale layers. Furthermore, by using natural Gamma ray separately determine amount of each element and by table provided by Schlumberger oil company we can identify Clay minerals.

Fig 2, shown some part of Maroon 246 well log graph in which from left, in track 1 the log of natural Gamma with Gamma ray spectrum, in track 2 the log of proportion radioactive elements (Th/U, U/K, Th/K) and in track 3 separated log of radioactive elements U, Th, K have been written. The measure of each element in each section is obtained by using this logs. Also the type of Clay minerals will identified by using log Pef data and Schlumberger company charts.

2. XRD Analysis method:

X-ray diffraction method is one of the pragmatic and appropriate methods in detection and analysis of micro particle materials such as Clay minerals. Providing samples for XRD experiment has the follow steps:

A) sample washing.

B) grinding.

C) providing liquid.

D) providing slides.

From all three slides for each sample, the slides are examined for thermal and Ethylene Glycol treatment and the third one as usual slide and by using obtained (fig 3) of each treatment, mineral forming, samples were detected. Thermal slide for 2 hours is exposed to 550 [degrees]C heat. Although because of the impact of factors such as crystalline, combination, impurities, orientation of Clay minerals and calibration analysis, quantitative measurement of the Clay quantity face problems but we can minimize the error rate by creating the same condition in providing and conductinganalysis.in addition, half quantitative methods are presented to estimate Clay minerals proportion:

[I.sub.Kaolinite/2.5] + [I.sub.Illite] + [I.sub.Montmorillonite] + [I.sub.Cholorite/2] = 100%

Discussion and Conclusion:

Among these minerals, Illite has the most quantity and is studied as main mineral in formations which is increased with increasing depth but in Gurpi middle zone it's quantity decreases.Faded emerging of montmorillonite in Maroon oil field can be considered due to marine condition or to convert a part of it to Illite. Clay minerals seldom are formed with the same structure and most of natural Clays are mixed of regular or irregular chains of Illite-montmorillonite (mixed layer). This type of mixed layer mineral is more common than others.

Having high rate of chlorite in Maroon indicates the different deposition or diagenetic conditions of formations. The middle part of Pabdeh formation and Gurpi formation in Ahwaz and Maroon oil field is composed of considerable Clay minerals such as montmorillonite which always in drilling process causes many problems. Most of Stuck drill pipes in these two zone has been reported, Which has imposed heavy and extra costs to the drilling operation. During drilling operation and with mud filtrate penetrate, and swelling of these minerals near the wellbore make production channels closed, permeability reduced and formation damaged. Knowing the condition of Clay minerals distribution in each formation provide economy in supply costs in drilling fluid and water injection, fluid treatment in each condition will be down. These reactions include using Materials preventing Shale swelling such as using oil base muds, Glycol drilling mud system and additives such as Potassium chloride (KCl) Calcium Chloride (CaCl2).

Appendix:

Schlumbrgers Cross Plots for clay minerals identification.

REFERENCES

[1] Faruk Civan, 2000. "Reservoir Formation Damage",Gulf Publishing Company, ISBN 0-88415-301-0.

[2] Muecke, T.W., 1979. " Formation Fines and Factors Controlling Their Movement in Porous Media"., 7007PA SPE Journal Paper.

[3] Changa, F.F., Faruk Civan, 1997. " Practical model for chemically induced formation damage"., Journal of Petroleum Science and Engineering, 17(1-2): 123-137.

[4] Civan, Faruk, 2007. " Formation Damage Mechanisms and Their Phenomenological Modeling--An Overview "., 107857-MS SPE Conference Paper.

[5] Civan, Faruk, 1999. "Interpretation and Correlations of Clay Swelling Measurements"., 52134-MS SPE Conference Paper.

[6] Nima mohamadian, A., Ghaderi, 2012. Comparing the distribution of clay minerals in Asmari, pabdeh and Gurpi formation, in Maroon and Ahvaz oil fields using two methods ; diagram of well logging and XRD methods. 1st International Conference on Oil, Gas, Petrochemical and Power Plants, Tehran, iran.

[7] Soleymani, B., H. sheykhzadeh, 2011. The Study of Clay minerals and illite crystallinity index in Asmari formation:Maroon oil fields . 15th Conference of crystallography and mineralogy , Ferdowsi University of Mashhad, mashhad, iran.

[8] Abbasi, S., A. Shahrabadi, 2010. Experimental Study on Effects of clay in the reservoir rock permeability reduction in water injection process in hydrocarbon reservoirs, Enhanced oil recovery Iranian Chemical Engineering Journal (special issue) (no 43). Shale Stability With Water Base Muds, 2007. Principal Investigator:Martin E.Chenevert, Mukul M. Sharma,.

[9] Carrol, D., 1970. Clay minerals; A guide to their X-Ray Identification, Special Paper 126, Geo. Soc.Am., Boulder, Colorado.

[10] Carver, R.E., 1971. Procedures in sedimentary petrology, John Wiley & Sons, Inc., 652.

[11] Elsinger, E. and D. Peavar, 1988. Clay minerals for petroleum geologist and engineers, Soc. Econ.Paleontol, Mineral short course- Notes, 22.

[12] Zhou, Z., W.D. Gunter, B. Kadatz, S. Cameron, 1996. "Effect Of Clay Swelling On Reservoir Quality",.9607-02 PETSOC Journal Paper.

[13] Zhou, Z., W.D. Gunter, B. Kadatz, Gunter, D. William, 1997. "Clay Swelling Diagrams: Their Applications in Formation Damage Control", 31123-PA SPE Journal Paper.

[14] Civan, F., R.M. Knapp, 1987. "Effect of Clay Swelling and Fines Migration on Formation Permeability",16235-MS SPE Conference Paper.

[15] Zhou, Zhihong, 1995." Construction and Application of Clay-Swelling Diagrams by Use of XRD Methods",29224-PA SPE Journal Paper.

[16] Moghadasi, J., M. Jamialahmadi, H. Muller-Steinhagen, A. Sharif, M.R. Izadpanah, 2002. "Formation Damage in Iranian Oil Fields",.73781-MS SPE Conference Paper.

[17] Moghadasi, J., Sharif, Adel Obaid, Kalantari-Dahaghi, A. Motaie, Eghbal, 2006. "A New Model to Describe Formation Damage during Particle Movement and Deposition in Porous Media", 99391-MS SPE Conference Paper.

Nima Mohammadian and Hamzeh Ghorbani

Department of Petroleum Engineering, Islamic Azad University_Omidiyeh Branch, Iran.

ARTICLE INFO

Article history:

Received 12 October 2014

Received in revised form 26 December 2014

Accepted 1 January 2015

Available online 17 February 2015

Corresponding Author: Nima Mohammadian, IAU Omidiyeh branch, Department of petroleum engineering, Omidiyeh, Iran Tel: +989358261035; E-mail: nima.0691@gmail.com

Table 1: Clay minerals of maroon oilfield.

Well no &   Depth   Illite   Kaolinite   Mixed
Formation    (m)                         Layer

291-Z3-As   2498      35        13        36
204-Z3-As   2500      23        30        30
224-Z3-As   2724      53         0         0
224-Z3-As   2763      29       41.5        0
291-Z4-As   2536      42         0        28
291-Z4-As   2664      69         0         0
291-Z4-As   2704      38         0        30
204-Z4-As   2680      43         0         0
204-Z4-As   2690      28        27        21
204-Z4-As   2717      38        23        29
205-Z5-As   2788      42        24         0
218-L-As    2773      59       21.5        0
Average             42.24       15       14.5
218-As-Pb   2811      77         0         0
291-Pb      2824      42         0        28
Average              59.5        0        14
267-Gu      3140      34         0        25
267-Gu      3250     30.5        0       36.5
Average               32         0       30.7

Well no &   Chlorite   Montmorillonite   Vermiculite
Formation

291-Z3-As      0             16               0
204-Z3-As      0             17               0
224-Z3-As      0            23.5            23.5
224-Z3-As      0            11.5             18
291-Z4-As      11            19               0
291-Z4-As      12            19               0
291-Z4-As      9             23               0
204-Z4-As      0             36              21
204-Z4-As      0              0              24
204-Z4-As      0              0               0
205-Z5-As      0             34               0
218-L-As      19.5            0               0
Average       4.3           16.6             7.2
218-As-Pb      23             0               0
291-Pb         9             21               0
Average        16           10.5              0
267-Gu         11            30               0
267-Gu         15            18               0
Average        13            24               0

Table 2: Clay minerals of Ahwaz oilfield.

Well no       Depth   Illite   Kaolinite   Mixed
& Formation    (m)                         Layer

202-L-AS      2734      25        22         0
248-L-AS      2744      26       14.5        0
216-L-AS      2822      25        53         0
206-L-AS      2946      30        18        19
234-L-AS      2960      39        45        16
206-L-AS      2964     35.5      32.5        0
Average                 30       30.8        6
202-As-Pb     2822      33        29         0
226-As-Pb     2840      27       38.3       13
216-As-Pb     2929      32        22         0
Average                 31       29.7       4.3
228-T-Pb      2955      31        27        15
203-U-Pb      2888      38        28        15
211-U-Pb      2966      45        27         0
230-U-Pb      2966      19       44.2        0
250-U-Pb      2920      30       28.6        0
231-U-Pb      3055      31       12.8        0
235-U-Pb      3058      27        24        14
Average                31.6       27        6.3
228-M-Pb      3026      36         0         0
211-M-Pb      3008      33        13         0
Average                34.5       6.5        0
239-L-Pb      3120      49         0         0
234-L-Pb      3186      47        21         0
Average                 48       10.5        0
226-T-Gu      3013      41        15         0
206-U-Gu      3154      36        13        19
226-U-Gu      3054      48        19        33
209-U-Gu      3057      38        21         0
Average                 38        17        13
202-M-Gu      3100      28        10         0
212-M-Gu      3139      31        13         0
211-M-Gu      3202      30         3         0
223-M-Gu      3221      32        18         0
228-M-Gu      3228      42        20         0
207-M-Gu      3250      48         0         0

Well no       Chlorite   Montmorillonite   Vermiculite
& Formation

202-L-AS         10            20              23
248-L-AS        22.5           13              24
216-L-AS         0              8              14
206-L-AS         0              0              33
234-L-AS         0              0               0
206-L-AS         0             13              19
Average         5.5             9              19
202-As-Pb        7             19               0
226-As-Pb       6.7             0              15
216-As-Pb        0             19              27
Average         4.6           12.6             14
228-T-Pb         0              0              27
203-U-Pb         0              0              19
211-U-Pb         0             28               0
230-U-Pb        12.8            7              17
250-U-Pb        4.4             0              37
231-U-Pb        14.2           14              28
235-U-Pb         0             12              23
Average         4.5            8.7            25.5
228-M-Pb        8.5            22             33.5
211-M-Pb         0             24              30
Average         4.2            23             31.7
239-L-Pb         17             0              34
234-L-Pb         13            19               0
Average          15            9.5             17
226-T-Gu         12             0              32
206-U-Gu         0              0              32
226-U-Gu         0              0               0
209-U-Gu         0              0              41
Average          3              0             26.2
202-M-Gu         0             27              35
212-M-Gu         0             25              31
211-M-Gu         22            45               0
223-M-Gu         0              0              50
228-M-Gu         0              0              38
207-M-Gu         22            30               0
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Author:Mohammadian, Nima; Ghorbani, Hamzeh
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Mar 1, 2015
Words:2398
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