## 1 Introduction  
Numerous applications for multiphase flow meters exist in the petrochemical and oil industries. For instance, there is a need to monitor multiphase flow continuously at some points. Some of these points include the gas-oil separator units and the wellhead collection lines. Monitoring at these points is of great value. The three-phase flow's volume fraction can be determined through several methodologies. One of the best methodologies is the gamma radiation-based technique, which is a nondestructive and reliable tool. Several studies have covered this area. One of the earliest studies was conducted in 1980, when [PERSON] and [PERSON] introduced a method for metering three-phase flow. That is the dual-energy gamma-ray attenuation-based method [1]. In their study, [PERSON] et al. (2005) presented the dual-energy gamma-ray method. The method aimed to examine the volume fraction of various components on the multiphase pipe flow cross-section of gas-oil-water [2]. With the intent to measure the attenuation dose rate of the material,there was a need to design a data acquisition system and nuclear instruments. After designing the data acquisition system and the nuclear instruments, static tests followed. Oil-water-gas media has three phases. These phases were investigated to test the hypothesis that they effectively simulate different distributions of media volumetric fraction. The three phases were investigated when the oil-water-gas media was used in experimental vessels. During this investigation, the measurements of attenuation intensities were taken. There was also a study of the volumetric fraction's equations and the linear attenuation coefficients' arithmetic. When the attenuation equations were investigated for unexpected measurement error, the involvement of modified arithmetic was disclosed. Besides, the experimental research revealed that the system's accuracy was acceptable. In their study, [PERSON] et al. (2009) measured a three-phase flow volume fraction using the gamma radiation technique [3]. They used two radioactive sources whose energies were different. They also used three NaI detectors. In their estimation of the gas-oil-water's volume fraction, the researchers were aided by the artificial neural network (ANN). They considered several flow regimes in this process. The researchers replicated this methodology in 2010 to recognize the homogenous, stratified, and annular flow regime. They then estimated the water-gas-oil multiphase systems' volume fraction [4]. [PERSON] et al. (2011) measured phase fractions using a traversable gamma radiation-based instrument [5]. There was a need to ensure that the noisy measurements yielded relevant data. Therefore, the researchers had to be careful in their data analysis. In this regard, the researchers used the two-phase and single-phase flow calibration data and tested the three-phase flow data analysis technique against this data. The researchers found that the traversable gamma instrument's average density data was significantly related to the calibrated, stationary, single-energy gamma instrument's density measurements. However, more information was obtained from the traversable densitometer than from the single energy instrument. The rationale behind this is that it was possible to measure all the three phases' transient phase fraction over the pipeline's cross-section. By using this information, the flow pattern could be determined. Further studies in field of multiphase flow meters can be found in references [6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25]. According to the literature review, in the systems that used gamma radiation technique to determine the oil, water, and gas volume fraction, the existence of the scale layer's has not been considered. The scale layer forms gradually as mineral salts are deposited on the oil pipeline's inner surface. An example of such a layer is shown in Figure 1.  
When the scale layer is compared to the fluid flow inside the oil pipeline, its density tends to be higher.