Exploration

Exploration activities are aimed at finding new volumes of hydrocarbons, thus replacing the volumes being produced. The success of a company s exploration efforts determines its prospects of remaining in business in the long term. 

The main facets of the oil and gas industry are exploration, production, refining, transportation and marketing. A brief description of each of these sectors is provided in this chapter. Although some petroleum companies are fully integrated with each of these operations others are segmented and only operate in their particular area of expertise or highest financial return. 

Seismic techniques, the reflection and refraction of sound or shock waves propagated through the earth, are also used to reveal details of the structure and interrelationship of various layers in the subsurface. The shock or sound waves record densities in the earth s surface that may indicate an oil or gas reservoir. Explosive charges or vibration devices are used to impart the required shock wave. 

Ultimately the only way to prove that oil is present underground is to drill an exploratory well. Most of the 

Corrosion is one of the problems that must be reckoned with in the successful drilling and completion of an oil or gas well. Recognition of the causes of corrosion in this environment, as in others, has led to the development of numerous corrosion control techniques. 

It is well known that environmental components such as oxygen, carbon dioxide, hydrogen sulfide, and dissolved salts accelerate corrosion attack. These corrosion accelerators are conunonly encountered in drilling and completion fluids and in many instances all are present. 

To offset their corrosive effects several techniques are used, including dilution, concentration, precipitation, neutralization, and chemical inhibition. Living organisms are not usually classified as corrosion contaminants, but they have the ability to produce corrosives to the extent that they, too, are an important consideration in corrosion control. 

Corrosion and Materials Selection A Guide for the Chemical and Petroleum Industries, First Editim. Alireza Bahadori. 2014 John Wiley Sons, Ltd. Published 2014 by John Wiley Sons, Ltd. 

1 Factors Important in Corrosion Attack During Drilling and Their Controi 

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Figure 1.46 shows a flowsheet without any heat integration for the different reactor and separation system. As before, this is probably too inefficient in the use of energy, and heat integration schemes can be explored. Figure 1.5 shows two of the many possible flowsheets. 

Before we can explore how reactor conditions can be chosen, we require some measure of reactor performance. For polymerization reactors, the most important measure of performance is the distribution of molecular weights in the polymer product. The distribution of molecular weights dictates the mechanical properties of the polymer. For other types of reactors, three important parameters are used to describe their performance ... 

If the problem in the absence of significant constraints can be decoupled in this way, there must be some mechanism which allows this, and that mechanism should be explored. 

Let us take each of these components in turn and explore whether they can be accounted for from the material and energy balance without having to perform heat exchanger network design. 

However, in the early stages of design, decisions that have important safety implications must be made based on an incomplete picture. Let us explore simple quantitative measures which can be used to assist decision making in the early stages of design. 

In Chap. 12 it was discussed how the pinch takes on fundamental significance in improving heat integration. Let us now explore the consequences of placing reactors in different locations relative to the pinch. 

The consequences of placing distillation columns in different locations relative to the pinch will now be explored. There are two possible ways in which the distillation column can be integrated. The reboiler and condenser can be integrated either across the pinch or not across the pinch. 

Having explored the major degrees of freedom, the material and energy balance is now fixed, and hence the hot and cold streams which contribute to the heat exchanger network are firmly defined. The remaining task is to complete the design of the heat exchanger network. 

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled. 

Combining informativeness and accuracy with readability, Stephanie Yanchinski explores the hopes, fears and, more importantly, the realities of biotechnology - the science of using micro-organisms to manufacture chemicals, drugs, fuel and food. 

This Hydrocarbon Exploration and Production is going to take you through all of the major stages In the life of an oil or gas field from exploration, through appraisal, development planning, production, and finally to decommissioning. 

TRACS International has provided training and consultancy In Exploration and Production related issues for many clients world-wide since 1992. This book has gradually developed from course materials, discussions with clients and material available in the public domain. 

Keywords exploration, appraisal, feasibility, development planning, production profile, production, abandonment, project economics, cash flow... 

Fortunately, the development of new exploration techniques has improved geologists understanding and increased the efficiency of exploration. So although targets are getting... 

Despite such improvements, exploration remains a high risk activity. Many international oil and gas companies have large portfolios of exploration interests, each with their own geological and fiscal characteristics and with differing probabilities of finding oil or gas. Managing such exploration assets and associated operations in many countries represents a major task. 

Even if geological conditions for the presence of hydrocarbons are promising, host country political and fiscal conditions must also be favourable for the commercial success of exploration ventures. Distance to potential markets, existence of an infrastructure, and availability of a skilled workforce are further parameters which need to be evaluated before a long term commitment can be made. 

Traditionally, investments in exploration are made many years before there is any opportunity of producing the oil (Fig. 1.2). In such situations companies must have at least one scenario in which the potential rewards from eventual production justify investment in exploration. 

Figure 1.2 Phasing and expenditure of a typioal exploration programme...

Once an exploration well has encountered hydrocarbons, considerable effort will still be required to accurately assess the potential of the find. The amount of data acquired so far does not yet provide a precise picture of the size, shape and producibility of the accumulation. 

The production phase commences with the first commercial quantities of hydrocarbons ( first oil ) flowing through the wellhead. This marks the turning point from a cash flow point of view, since from now on cash is generated and can be used to pay back the prior investments, or may be made available for new projects. Minimising the time between the start of an exploration campaign and first oil is one of the most important goals in any new venture. 

Even if all of the elements described so far have been present within a sedimentary basin an accumulation will not necessarily be encountered. One of the crucial questions in prospect evaluation is about the timing of events. The deformation of strata into a suitable trap has to precede the maturation and migration of petroleum. The reservoir seal must have been intact throughout geologic time. If a leak occurred sometime in the past, the exploration well will only encounter small amounts of residual hydrocarbons. Conversely, a seal such as a fault may have developed early on in the field s history and prevented the migration of hydrocarbons into the structure. 

Given the costs of exploration ventures it is clear that much effort will be expended to avoid failure. A variety of disciplines are drawn in such as geology, geophysics. 

The objective of any exploration venture is to find new volumes of hydrocarbons at a low cost and in a short period of time. Exploration budgets are in direct competition with acquisition opportunities. If a company spends more money finding oil than it would have had to spend buying the equivalent amount in the market place there is little Incentive to continue exploration. Conversely, a company which manages to find new reserves at low cost has a significant competitive edge since it can afford more exploration, find and develop reservoirs more profitably, and can target and develop smaller prospects. 

Eventually, only the drilling of an exploration well will prove the validity of the concept. A wildcat ls drilled in a region with no prior well control. Wells may either result in discoveries of oil and gas, or they find the objective zone water bearing in which case they are termed dry . 

Exploration activities are potentially damaging to the environment. The cutting down of trees in preparation for an onshore seismic survey may result in severe soil erosion in years to come. Offshore, fragile ecological systems such as reefs can be permanently damaged by spills of crude or mud chemicals. Responsible companies will therefore carry out an Environmental Impact Assessment (EIA) prior to activity planning and draw up contingency plans should an accident occur. In Section 4.0 a more detailed description of health, safety and environmental considerations will be provided. 

It is fair to say that advances in seismic surveys over the last decade have changed the way fields are developed and managed. From being a predominantly exploration focused tool, seismic has progressed to become one of the most cost effective methods for optimising field production. In many cases, seismic has allowed operators to extend the life of mature fields by several years. 

To type crude oils (see Figure 2.13). This method uses an extremely accurate compositional analysis of crudes to determine their source and possible migration route. As a result of the accuracy It is possible to distinguish not only the oils of individual accumulations in a region, but even the oils from the different drainage units within a field. If sufficient samples were taken at the exploration phase of a field, geochemistry allows one to verify cross flow and preferential depletion of units during later production. 

Over the last decade some of the major oil companies have been using vast amounts of outcrop derived measurements to design and calibrate powerful computer models. These models are employed as tools to quantitatively describe reservoir distribution and flow behaviour within individual units. Hence this technique is not only important for the exploration phase but more so for the early assessment of production profiles. 

The technique of mudlogging is covered in this section because it is one of the first direct evaluation methods available during the drilling of an exploration well. As such, the mudlog remains an important and often under-used source of original information. 

In summary, exploration activities require the integration of different techniques and disciplines. Clear definition of survey objectives is needed. When planning and executing an exploration campaign the duration of data acquisition and interpretation has to be taken into account. 

Imagine for a moment that the exploration activities carried out in the previous section have resulted in a successful discovery well. Some time will have passed before the results of the exploration campaign have been evaluated and documented. The next step will be the appraisal of the accumulation, and therefore at some stage a number of additional appraisal wells will be required. The following section will focus on these drilling activities, and will also investigate the interactions between the drilling team and the other E P functions. 

The survey requirements will depend on rig type and the extent of the planned development e. single exploration well or drilling jacket installation. Atypical survey area is some 4 km by 4 km centred on the planned location. Surveys may include... 

A slim hole rig weighs about one fifth of a conventional rig and its small size can open new frontiers by making exploration economic in environmentally sensitive or inaccessible areas. 

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