In present scenario the applications of numerical reservoir simulators are very wide and extensive. Simulation is the only tool to describe quantitatively multi-phase flow in a heterogeneous reservoir. But, nowadays most of the users of reservoir simulators are becoming the hostages of computer-generated results, even though, many incorrect analysis techniques, mathematical models and computational approaches are used extensively in reservoir simulation study. This paper revealing such incorrect but commonly accepted approaches presents alternate and correct mathematical approaches for the advancement of simulators. First of all authors take privilege of their previous work where, through wide literature survey, various examples (e.g. fracture and shale flow solutions where fine mesh discretization technique may lead to erroneous results due to singular velocities at the fracture and shale tips, fracture flow modeling using discrete point source which was replaced by continuous line source, etc.) of incorrect models were shown and proved to be the source of erroneous results and numerical instability [5]. After revealing such incorrect models, the solutions for eliminating this incorrect techniques and models are presented and proved numerically and analytically. Mathematical techniques and formulations used in this paper are finite element method, finite volume method, advanced conformal mapping, streamfunction and streamline tracing, modern singular integral equation approaches, moving boundary value problems technique, artificial viscosity analysis, generalization of coordinate system, curvilinear grid generation, integral transformations, etc., which stabilize the mentioned simulation models. The recent technological innovations in drilling and production and complicated reservoir studies have challenged the existing simulators so is the key target of this paper is to move in direction of the next generation simulators that can solve the various mentioned inaccuracies. Various accurate mesh generation algorithms are anticipated to develop through this paper to revolutionize the modern reservoir simulation study.

In a present scenario the applications of numerical reservoir simulators are very wide and extensive. Simulation is the only tool to describe quantitatively multi-phase flow in a heterogeneous reservoir. But, nowadays most of the users of reservoir simulators are becoming the hostages of computer-generated results, even though, many incorrect analysis techniques, mathematical models and computational approaches are used extensively in reservoir simulation study. This paper reveals such incorrect but commonly accepted approaches and presents alternate and correct mathematical approaches for the advancement of new generation reservoir simulators. Firstly, wide literature survey is done and presented to show the mathematical approaches that are applied presently to the simulators. Then various examples (e.g. fracture and shale flow solutions where fine mesh discretization technique may lead to erroneous results due to singular velocities at the fracture and shale tips, fracture flow modeling using discrete point source which is replaced by continuous line source, etc.) of incorrect models are shown and proved to be the source of erroneous results and numerical instability. After revealing such incorrect models, the solutions for eliminating this incorrect techniques and models are presented and proved numerically and analytically. Mathematical techniques and formulations used in this paper are advanced conformal mapping, streamfunction and streamline tracing, modern singular integral equation approaches, moving boundary value problems technique, artificial viscosity analysis, generalization of coordinate system, curvilinear grid generation, integral transformations, etc. which stabilize the mentioned simulation models. In recent years the technological innovations in drilling and production and complicated reservoir studies have challenged the existing simulators so is the key target of this paper is to move in direction of the next generation simulators that can solve the various mentioned inaccuracies. Various accurate mesh generation algorithms are developed in this paper to revolutionize the modern petroleum engineering.

Applicability, assessment and work-how of Micro-Wave Assisted Gravity Drainage (MWAGD) process in Mehsana (India) heavy oil field along with added advantages over SAGD were presented in the previous part of this paper [1]. Various studies have been done during last 10 years illustrating wider applications of micro-wave heating of heavy oil reservoirs through quantitative and qualitative exercises. But the main problem that arises in micro-wave heating is very low penetration depth of micro-wave radiations which limits the application of this unconventional thermal EOR method on full field scale. The scope of this paper is to eliminate this problem by using horizontal well pair combination which enhances the drainage area within the heating radius of micro-wave radiations.The phenomenon of conversion of Micro-wave energy to heat energy is described and finally, a mathematical model based on energy balance principle is developed. Two parallel and vertically aligned horizontal wells are drilled. The upper well is production well and lower well is micro-wave source well with their length and vertical separation on the order of 500 meters and 15 meters respectively. In the lower well micro-wave sources are installed at various positions along the length with longitudinal spacing on the order of 20 meters. Advantages of heating of oil from the lower well are explained in lucid manner. This type of installation model confirms the coverage of larger reservoir volume in spite of short penetration depth of micro-wave radiations. Along with volumetric and selective heating in this process heat is developed within the formation fluid rather than being brought to it from the outside, and hence the fluid is heated more uniformly throughout the medium. Also, above proposed model can be applied effectively in case of carbonate formations where uneven sweeping occurs along steam assisted gravity drainage (SAGD) well pairs due to vuggs and fractures.

India with the largest gas hydrate deposits in the world have potential of being the biggest global producer of NGH (a solidified form of gas lying on oceanic floors). 1.08 trillion cubic metres of the proven conventional natural gas reserves in India is around 1700 times less than the prognosticated gas hydrate resources of 1,894 trillion cubic metres lying in the deep water regions. Even the extraction of minor fraction of this resource can be the energy hunters for decades.This paper discusses the geological and geophysical aspects of marine gas hydrate distribution in India. Through a wide literature survey authors have shown the hurdles which are imposing constraints on the wide scale extraction of natural gas from NGH. The Indian exploration strategies to identify and quantify the gas hydrates by various seismic tools (e.g. seismic reflectors coincidence with the base of the gas hydrate stability zone (BGHSZ)) with its limitations are described in lucid manner. Also, the technical advancements are presented to eliminate the mentioned limitations. Well- based extraction technology (a drilling program) is discussed for safe and economically viable production of gas from gas hydrate reservoirs.India's 7500 km of coastline having a vast fuel reserve in the form of NGH can be a next generation energy source if mature extraction technology is developed to extract the gas from gas hydrate reservoirs.