Development of a fuzzy system model for candidate-well selection for hydraulic fracturing in a carbonate reservoir

With current technology, it is only possible to extract 20% to 25% of the original oil in place from Iranian carbonate reservoirs, 10% less than the world average. In addition, formation damage is a serious problem in those reservoirs, which mainly caused by asphaltene precipitation, sand production, and ineffective stimulation method. The majority of mature carbonate reservoirs in Iran have low permeability and high skin values. Therefore, such reservoirs are capable of producing at commercial rates only if they are hydraulically fractured. Acid fracturing is usually reported as a standard method for fracturing in carbonate reservoirs. Hydraulic Fracturing (HF) technology, which was originally applied to overcome near wellbore damage, is a proper replacement stimulation method. It is evident that to adopt this technology, considerable efforts have to be strenuous in candidate-well selection. As asserted in the literature, even though a common practice, candidate-well selection is not a straightforward process and up to now, there has not been a well-defined approach to address this process. The techniques applied in HF candidate-well selection could be divided into two methods; conventional and advanced approaches. Conventional methods are not easy to use for nonlinear processes, such as candidate-well selection that goes through a group of parameters having different attributes and features such as geological aspect, reservoir and fluid characteristics, production details, etc. and that's because it is difficult to describe properly all their nonlinearities. However, it is believed that advanced methods such as Fuzzy Logic (FL) could be better decrease the uncertainty existed in candidate-well selection. This paper presents a Mamdani fuzzy model where rules for HF candidate-well selection were derived from multiple knowledge sources such as existing literature, intuition of expert opinion to verify the gathered information. The needs for adapting HF as replacement stimulation in Iranina carbonate reservoirs are discussed and advanced methods for HF candidate selection will be reviewed in this paper. Also, the main reasons which show why propped HF is the choice in carbonate reservoirs will be discussed. Finally, the proposed Fuzzy system model is applied along with a case study in a carbonate reservoir

A review on conventional candidate-well selection for hydraulic fracturing in oil and gas wells

Hydraulic Fracturing (HF) which is an ever-increasing focus area for upstream industry is the pumping of fluids at high rates and pressures in order to break the rock, and it is using to accelerate hydrocarbon production and improving ultimate recovery in many reservoirs. It is clearly indicated in HF experience's literature, to be successful conducted, it is directly depending on rigorous candidate-well selection. The techniques applied in HF candidate-well selection could be divided into two methods; conventional and advanced approaches. Being familiar with the conventional methods in candidate-well selection that mainly deals with engineering, geological, etc aspects in decision making process, is of particular importance in order to increase the performance of the advanced techniques that mainly utilized artificial intelligence methods. This paper is a review of the conventional candidate-well selection for hydraulic fracturing in oil and gas wells

Petroleum Chemicals - Recent Insight

A vast amount has been written about petroleum fuels, including books and guidelines; hence, we thought it timely to produce a book Petroleum Fuels: Recent Updates, which covers the most important areas in the topic. In its pages, we tried to include advances toward green and sustainable viable products in terms of biodiesel production and chemical transformation. The book contains rich extracts from experts in the fuel field, including technical/environmental and econometric aspects

Current Topics in the Utilization of Clay in Industrial and Medical Applications

This book presents recent developments and research activities that highlight the importance of clay science and engineering in the environment and medical and civil engineering. The book contains nine chapters separated into three main sections: (1) Clay for the Environment, (2) Clay in Civil Engineering, and (3) Clay in Medical Applications. There are four chapters in the first section and the focus is made on the topics related to an introduction to the natural sources and chemical structure of one of the important clay types, montmorillonite. The application of waste recycling and the removal of arsenic and fluoride are the focus of next two chapters. In addition, a technique for corrosion protection is presented as the fourth chapter within this section. In the second section, special emphasis has been placed on the importance and application of clay in civil engineering, which is demonstrated in two chapters. In the third section, new research and development on utilizing clay minerals in medical applications is presented. Intended for readers wishing to acquire an understanding of the current trends in clay science and engineering and comprehension of the issue, this book addresses exciting topics in this field

Application of polymers for coating of proppant in hydraulic fracturing of subterraneous formations: a comprehensive review

Polymers have extensively been employed by petroleum industry to maintain, treat and optimize drilling and production operation in oil and gas wells. Polymers minimize solid deposition in wells, maintain fluid viscosity, thicken water, reduce downtime caused by corrosion and maintenance work, but can also be used to clean well and surface equipment. One of the most widely forms of polymer application in oil and gas industry is related to coating of proppant in hydraulic fracturing (HF) operation. Proppants are small spheres that must have enough strength to withstand to high closure stresses. Application of polymers for coating of proppants is just emerging in recent years and promises higher performance by taking the both of strength and flexibility context into account. Coating of proppant with a thin layer of polymer will results in higher fracture conductivity, considerably reduce fines generation and scaling, thereby improving the quality of HF treatment. This paper reviews the polymer application for coating of proppants in HF treatment. The purpose of this article is three-fold: (1) to update petroleum and chemical scientists and engineers on the latest development in polymer utilization for coating of proppant, (2) to give some basic details on proppants and polymers to help understand why these developments came about and to (3) summarize the latest advances in proppant coating methods and procedures

Applications of type-2 fuzzy logic system: handling the uncertainty associated with candidate-well selection for hydraulic fracturing

The problem of selecting a target formation(s) in a reservoir among a vast number of zones/sub-layers within huge number of hydrocarbon producing wells for hydraulic fracturing (HF) by using interval type-2 fuzzy logic system (IT2-FLS) to maximize their net present value is studied in this paper. Classical fuzzy system which is called type-1 fuzzy logic system is not capable of accurately capturing the linguistic and numerical uncertainties in the terms used and the inconsistency of the expert’s decision-making. IT2-FLS is very useful in circumstances where it is difficult to determine an exact membership function for a fuzzy set; hence it is very effective for dealing with uncertainties. In highlighting this need, the question has been answered why IT2-FLS should be used in this study. The procedure of applying this study in the area of HF candidate-well selection is illustrated through a case study in an oil reservoir

The use of nano-sized Tapioca starch as a natural water-soluble polymer for filtration control in water-based drilling muds

A new additive derived from Tapioca starch has been developed which is highly effective in filtration control in water-based drilling muds. Laboratory experiments were conducted for five different concentrations (0.5%, 1%, 1.5%, 2% and 2.5%) and three sizes (64μ, 7μ, and 920 nm). The nano-sized starch exhibited an improved fluid loss by 64.2% in the concentration of 2.5%, while reducing the mud cake thickness by 80.