John O. Robertson

Chapter 3 The Manufacture, Chemistry and Classification of Oilwell Cements and Additives

Publisher Summary The word cement denotes any kind of adhesive, whereas in the building industry it denotes a substance utilized to bind together sand and broken stone into a solid mass. The cement composition is often referred to as hydraulic because cement hydrates when mixed with water (into a paste). Then it sets and hardens because of chemical reactions between the water and compounds present in the cement. The manufacturing of Portland type cements involves heating to partial fusion of limestone, clay, iron, and aluminates. This chapter discusses several types of cement that are classified as (1) pozzolanic-portland cements, (2) pozzolan-lime cements, (3) resin or plastic cements, (4) gypsum cements, ( 5 ) diesel oil cements, (6) expanding cements, (7) refractory cements, (8) latex cements, and (9) cement for permafrost environments. The chapter also discusses the cement additives that are classified into accelerators, heavyweight additives, lightweight additives, retarders, filtration-control agents, lost-circulation control agents, friction reducers, and specialty materials.

Chapter 8 Waterflooding

Publisher Summary This chapter presents the various prediction techniques and provides details for the primary techniques. The chapter describes the major assumptions, data requirements and comparisons of methods. The chapter also provides detailed comparisons of alternate predictive techniques within the major groupings. Behavior of carbonate reservoirs is also discussed in the chapter. When considering the use of waterflooding for a specific reservoir, it is often valuable to get a quick look at the overall project economics. When considering the use of waterflooding for a specific reservoir, it is often valuable to get a quick look at the overall project economics. The selection of an injection pattern is one of the first steps in the design of secondary recovery projects. When making the choice, it is necessary to consider all the available information about the reservoir. The adverse effects of the other factors listed above can be partially offset if they are considered during the pattern selection. Other factors that should be considered in pattern selection are flood life, well spacing, injectivity, response time, and productivity.

Chapter 5 Miscible Flooding

Publisher Summary This chapter explains miscible flooding. Miscibility exists when two fluids are able to mix in all the proportions without any interface forming between them. Miscibility is controlled by the pressure, temperature, composition of the oil, and composition of the displacing fluid. The pseudo-ternary phase diagram is often used as an aid in understanding the miscibility process for complex hydrocarbon mixtures. In a gas-liquid system, a miscible bank is formed by either evaporation or condensation of the intermediate hydrocarbons. If the major transfer of intermediate hydrocarbons occurs by condensation from the gas, the system is known as enriched-gas or condensing-gas drive. If the major transfer of intermediate hydrocarbons is from the reservoir oil, then the system is known as high-pressure or evaporation-gas drive. It is now known that many of the unsuccessful miscible projects were improperly engineered. Some of the reasons for failure were improper patterns, insufficient pressure to achieve miscible displacement, and excessive reservoir heterogeneity. When the conditions are suitable for the attainment of miscibility, sweep efficiency determines the success or failure of a project. In this chapter, a discussion on sweep efficiency is presented. High-pressure gas injection is discussed. An overview of enriched gas drive is also presented in the chapter.

Chapter 4 Gas Injection

Publisher Summary This chapter discusses the gas injection technique. Gas injection is the oldest of the fluid injection processes. The idea of using a gas for the purpose of maintaining reservoir pressure and restoring oil well productivity was suggested as early as 1864, just a few years after the drilling of the Drake well. Since that time, injection of natural gas or other gases has been used successfully in many oil reservoirs throughout the world as a secondary recovery method. The early gas injection projects were designed to increase the immediate productivity and should be classified as pressure maintenance projects. However, recent gas injection applications have been intended to increase the ultimate recovery and can be considered as enhanced recovery projects. Gas injection may be either a miscible or an immiscible displacement process. The character of the oil and gas and the temperature–pressure conditions of the injection determine the type of process. Two major predictive techniques, the Welge and the Tarner, are discussed in this chapter. Recommended steps in using the Welge technique of gas-injected flood prediction are discussed. A discussion on reservoir performance is also presented in the chapter.

Chapter 4 Fracturing

Publisher Summary Hydraulic fracturing has played a major role in increasing the oil and gas reserves. In hydraulic fracturing, fluid is injected until the fluid pressure overcomes the stresses inherent in the rock or is greater than the forces holding the rock together. This causes the rock to split apart forming a fracture. Fracturing fluid must be pumped into the fracture rapidly enough to hold the fracture open and allow the propping agent carried by the fluid to enter the fracture and hold it open. In some cases, a propping material is not used. If there is no propping agent present to hold the walls of the fracture apart, however, the fracture walls can close or “heal.” Fracturing creates new and larger flow channels through the damaged zones, around the wellbore. Fractures then extend out into the undamaged portions of the reservoir and may connect the preexisting natural fractures and microfractures to the wellbore. In tight reservoirs, fractures create a much larger drainage surface area.

Chapter 5 Acidizing Oilwells

Publisher Summary Advancements in the science of oil well acidizing have been mainly in the use of additives to improve acid performance and handle a wide range of problems. Great strides have been made in the development of (1) surfactants to reduce emulsion formation, improve wettability of rock by acid, to speed cleanup, and prevent sludge formation, (2) inhibitors to reduce corrosion, (3) buffering agents to control pH, (4) retarders to retard reaction rates, and (5) friction reducers. This chapter discusses the purpose of oil well acidizing and acid types. The primary purpose of acidizing an oil well is to increase fluid production by improving the drainage efficiency of the reservoir rock around the wellbore. Acidizing is particularly applicable to those oil wells producing from carbonate formations or clastics in which the cementing material is composed of carbonates. Many types of acids that are used in acid stimulation of oil wells, fall into two major categories—organic and inorganic.

Chapter 12 Gas Lift

Publisher Summary This chapter provides an overview of a gas lift. The subsurface gas-lift installations can be divided into three types: (1) fluid discharge occurs up the tubing with gas being injected into the annular space; (2) fluid discharge occurs up the annular space with gas being injected down the tubing; and (3) there are two connected tubings, with gas being injected down one and fluids being lifted in the other. The initial steps in the design of continuous flow gas lift systems include determination of—(1) the point of gas injection, (2) gas volume required, and (3) the injection pressure. The intermittent gas lift system involves expansion of a high-pressure gas bubble or slug ascending to a low-pressure outlet. Complete pressure and volume expansion control of gas entering the tubing is handled by a valve with a large port. It either regulates the lift of the accumulated fluid head above the valve with a maximum velocity to minimize slippage, or controls liquid fall back by fully ejecting it to the tank with minimum amount of gas. Intermittent gas lift is often used in conjunction with a surface time controller.

Chapter 1 Introduction to Surface Production Equipment

Publisher Summary This chapter provides an introduction to surface production equipments. One of the equipments is the gathering system that consists primarily of pipes, valves, and fittings necessary to connect the wellhead to the separation equipment. The gathering system may contain one or more lines with branches to each well, or it may consist of separate lines from each well, which are connected to a group header or test header system, as distance and distribution dictates. Storage tanks are usually of bolted construction up to the 10,000-barrel size. Welded steel tanks are used extensively in the larger sizes. In some fields, small welded steel tanks in bolted tank sizes up to 500 bbl are used. Accessory equipment includes the equipment that is not basically necessary to convey the oil from the wellhead to the pipeline or other means of transportation. Vapor recovery, water treatment, and automatic custody transfer are included in this group. Oil and gas separators are used in most petroleum production operations. The primary function of these separators is to produce gas-free liquid and liquid-free gas. Basically there are three types of separators: vertical, horizontal, and spherical. Each type has proven features particular to various field applications.

‘Swellmeter’: An Apparatus for Measuring the Degree of Swelling of Clays

Abstract Swelling of clays in reservoir rocks (formation damage) is of utmost importance to petroleum engineers. Various inorganic and organic chemicals can be used to prevent swelling of clays. Design and operation of a simple apparatus for measuring the swelling of clays (a ‘swellmeter’) using various chemical solutions are presented in this paper.