Since the popularization of oil well acidizing during the 1930's the specific problem of acid corrosion of tubular goods has been a fertile yet frustrating field for the corrosion chemist. Included in this paper will be a brief discussion of corrosion theory which will serve as a prelude to a discussion of more recent research developments which point to new parameters critical to the understanding and development of environmentally-acceptable organic acid corrosion inhibitors for the deeper and hotter wells of the 70"s. Also included will be a discussion of the various stop-gas measures that have evolved in an attempt to minimize the problems inherent with the common organic inhibitors. These techniques include: "double inhibiting", inhibitor slugs," inhibitor extenders or intensifiers, acid blends, sulfide control additives and inhibitor solubizers. The latest research developments in the areas of inhibitor-to-metal surface area ratios, acid turbulence, fluid cooling effects, and variations in grade grades of tubular goods will be presented as well as a description of the test apparatus and test procedures used in developing a new highly effective organic inhibitor.

Stimulation of carbonates with acid has been and will continue to be one of the most economical means of improving the performance of both production wells and injection wells. Performance improvement is accomplished through the proper match-up of fluids and techniques to the reservoir The beginning of a successful stimulation starts with an understanding of the reservoir composition and pore system. Having defined these reservoir properties, an evaluation of fluids which will not only achieve the best differential etching in the carbonate but will also maintain rock integrity to withstand closure of conductivity pathways created by acidization comes next. Lastly, control of leak-off and reactivity for placement to insure deepest penetration and conductivity is considered. Presented are examples of implementation of the above evaluations, which have resulted in successful stimulations. These case histories cover a wide range of reservoir conditions and geographical areas.

One of the most effective methods of carbonate stimulation is acid fracturing. Development of fracture geometry sufficient to allow etched penetration to provide economic production increases is dependent upon several factors, one of which is pump rate. High rates and/or lower hydraulic horsepower requirements can be critical to success to one of these projects. Many times wells lack the integrity or flexibility to be treated down casing. Treating down tubing affords highly viscous fluid's opportunity for rate restrictions due friction pressure. In addition, fluids of high viscosity based on the crosslinking of polymers using zirconium are known to have shear limitations, and, therefore, high rates have been unattainable. Laboratory testing and case histories are presented regarding the evaluation and usage of zirconium crosslinked hydrochloric acid systems in the acid fracturing of several carbonates utilizing a variety of tubulars from 2-3/8 to 4-1/2 inch.

Mud solids can cause severe productivity impairment which can only be prevented by the use of acid-soluble muds. Conditions justifying the use of such muds are as follows: 1) Highly permeable formations (say above 500 md). 2) Carbonate reservoirs of low matrix permeability whose productivity depends on a fracture network. 3) In production repair wells where the risk of lost circulation into depleted reservoirs and of plugging established flow channels is high. 4) When it is advantageous to have an acid-soluble filter cake, e.g. when gravel packing, shot perforating, or if a good cement bond is required. Acid soluble, water-base fluids are composed of graded carbonate bridging particles whose maximum size must be equal to at least one third the largest expected pore opening. Filter loss control is best provided by an acid-soluble lignosulfonate and viscosity by hydroxyethyl-cellulose. Sodium chloride or calcium chloride brines and/or ground carbonates (44-2 microns) are used then higher weights are required. One type of acid-soluble oil-base fluid is an invert emulsion stabilized by treated carbonate fines. In others an oil-soluble colloid is used. In both cases ground carbonates are used for bridging and weighting. One problem that arises when drilling with acid-soluble fluids is the incorporation of insoluble drilled solids. This is minimized by not introducing the fluid until the top of the productive horizon is reached and by the greatest possible use of mechanical separation equipment. In production workover jobs, the most common problem is loss of circulation. To prevent or remedy this, the fluid is applied as a pill containing a high concentration of bridging solids.

This paper explains a new approach in choosing the most acceptable treating fluid and a history of field applications using the new method.

Acoustic instruments have been used routinely for many years as an aid in analyzing well performance of normal-pressure oil producers. Recent developments in equipment and techniques now permit more-accurate calculations of acoustic static bottomhole pressures at surface pressures up to 15,000 psi in corrosive (COP and H2S) environments. Equations and charts are presented herein for determining static bottomhole pressures from acoustic and well data. Also, a special technique is recommended for shutting-in a well which in most cases will yield more-accurate results. The bottomhole pressure of wells producing high concentrations of CO, gas can be determined from acoustic data and the tables and figures given herein. This method has been programmed for an inexpensive, portable notebook-size computer which can be used in the field to easily perform these calculations.

The ACE log is an efficient aid in determining the quality of reservoir isolation achieved through primary or squeeze cementing. A subject of controversy since its inception, cement bond evaluation has improved with advanced technology and with continued concern by the industry for an effective evaluation meth0d.l A better understanding of the operations principles by service company and operations personnel, meaningful calibration, and the application of logic to interpretation are some of the factors responsible for increased acceptance by the industry. Properly run ACE logs respond to downhole conditions that are present, which may or may not correspond to the expected conditions. Unlike formation evaluation logs, there are no correlative factors extending from well to well to act as repeatability checks. Each log must stand on its own, and its interpretation must be supported with logic. The lack of standardization of logging systems by service companies should not present an insurmountable problem to log quality or interpretation if proper basic logging principles are followed.

Electronic equipment is available to determine the fluid depth in oil wells quickly and accurately. The fluid depth is determined by producing a sound wave at the surface and recording the reflections on a strip chart. Therefore, the instrument is called an acoustical well sounder (AWS). The most common means of producing the sound waves is by firing a black powder blank into the annulus. Recent innovations of gas guns have improved the safety and performance, and decreased the cost of using as AWS. The acoustical well sounder is primarily used to determine producing fluid levels, shut-in levels, and fluid build-up curves of an oil well.

The Coalbed Natural Gas Industry, or Coalbed Methane (CBM) continues to gain global popularity and momentum. However today, CBM operations are one of economic challenges. Varying coal seam depths, rapidly declining water production rates, uncharacteristic well completions, sand, coal fines, etc., prohibit using just one form artificial lift equipment. Successful CBM production operations demand multiple product lines. Weatherford determined that a new approach was needed that offered multiple product lines in addition to modifications of conventional artificial lift products. A presentation will be prepared that outlines the challenges CBM production presents to operators. This paper and presentation will discuss old artificial production techniques and new approaches. Because there is a never-ending focus on lowering lease operating expenses (LOE) operators continue to push manufacturers into modifying and or developing new production products. Weatherford has a dedicated CBM team determined to lead the industry in CBM equipment development. This paper will offer some of Weatherford's solutions to this ever-demanding industry.

The Adjustable Valve Rod and Pull Tube Guide is designed to allow for precise spacing in a down-hole sucker rod pump. In historical installations the spacing is based on the valve rod or pull tube length. This length is usually in one inch increments from the factory, or the rod or tube is field cut and threaded to maximize the pump compression ratio. This patented guide allows the spacing to be adjusted with greater precision and will compensate for manufacturing tolerances and reduce field cutting and threading of pull rods and pull tubes. This paper will describe how the guide is designed, its specific applications and its advantages over conventional sucker rod and pull tube guides.

Virtually every oil production company and many gas producers, both major and independent, must use one or more forms of artificial lift to assist in producing their wells. Yet, most companies do not have artificial lift experts. In fact, many companies don"t even have engineers trained in artificial lift. And almost no companies have artificial lift research and development programs. In fact, most companies must depend solely on the service companies to provide the artificial lift technology, products, and services they require. But, all production companies face many challenges in the artificial lift arena to optimize the economic recovery of their hydrocarbon (both oil and gas) reserves. This is certainly true in the "green" field areas of horizontal, multi-lateral, deepwater, and sub-sea wells, and wells in challenging locations such as deserts, arctic environments, etc. It is also true in "brown" fields where even small percentage improvements in artificial lift effectiveness and efficiency can make the difference between a profitable and an unprofitable operation. If artificial lift is so important, and if "getting it right" is worth so much, why is there so little engineering focus on it? The answer seems to be that many companies consider artificial lift to be "old, existing, proven" technology, with little or no room for improvement. Many people feel that pumping or gas-lift is relatively simple. If the pump is going up and down, the well must be producing oil. If gas is being injected into the well, it must be producing by gas-lift. While these "feelings" may be true to some extent, it is often (perhaps normally) the case that the artificially lifted wells that do not receive much attention are operating very ineffectively and inefficiently. They are producing much less than they could; they are costing much more to operate than they should; and often both capital and repair and maintenance costs are much higher than necessary. This is not an idle claim. It has been proven, time and again, that an effective artificial lift surveillance program and application of appropriate artificial lift equipment and practices, can significantly increase production, reduce operating costs, reduce repair and maintenance costs, and often reduce capital expenditures. It has been proven that use of effective artificial lift processes, equipment, and practices can result in: Beam pumping wells - 5 - 10% more oil - 15 - 20% less energy consumption - 25 - 35% reduction in repair and maintenance costs Gas-lift wells - 5 - 10% more oil - 5 - 10% less gas-lift gas - Lower investments in compression equipment Electrical submersible pumping wells - 3 - 5% more oil - 6 - 12 months longer run times Being realistic, this is not a "pitch" to have every oil and gas production company hire an artificial lift engineering staff or start an artificial lift R&D department. Realizing that this is not going to happen, there is currently an effort underway to form an industry-wide organization to focus specifically on advancing the technology and "business" benefits of artificial lift by enhancing artificial lift technology, understanding, training, processes, equipment, practices, and applications. This industry initiative is called the Artificial Lift Research and Development Council (ALRDC).

"The Wellhead Scanalog is a new and effective approach to the evaluation of used oil field tubing. Designed to perform tubular inspection while the tubing is being pulled, it does not interfere with normal workover operations. The tool provides four non-destructive methods to detect and evaluate used tubing defects such as rodwear, corrosion pitting, erosion, holes, and splits. A new rotating magnetic field technique is used for rod wear, a modified flux leakage technique is used for pitting, and average wall measurements derive from a total flux concept. Eddy currents are used for holes and splits. Radiation techniques are not used for safety reasons. Sensing systems are non-contract, and not affected by scale, mud, paraffin and water, and there are no active or moving parts in the sensor package. The tool bolts directly onto the well head, and in many fields several wells can be inspected each day. Sequential inspection of tubes in over 5000 wells inspected has revealed well tubing profiles which provide useful diagnostic information for well servicing programmes."

The use of Variable Speed Drives to control Rod Pumps has been tried with varying results. The success has been limited due to issues such as surface equipment reliability, regeneration, voltage and current harmonics, poor power factor, and premature Rod, Tubing, and Pump failure. This paper describes a unique technology that combines the latest advances in power electronics with patented firmware and application software solutions resulting in optimized production and reduced maintenance and energy costs for heavy oil, high gas content and "problem" wells. The technology eliminates pump-off and allows the operator to maintain the fluid level at a predefined level above the pump, maximizing pump fillage, while accurately controlling the rod speed at all times preventing premature rod failure. This new technology also produces a near unity power factor and a minimum of voltage and current harmonics and allows the use of more cost efficient high efficiency NEMA B motors.

Acoustic liquid level tests are performed successfully in many different applications throughout the world. Advanced techniques for acoustic liquid level analysis are required for wells where unusual conditions exist such as very shallow liquid levels, annular partial obstructions, flush pipe, short tubing joints, etc. Some wells have liners, upper perforations, paraffin, odd length of tubing joints, poor surface connections and other conditions which result in an acoustic trace that may be very difficult to interpret. Normally, the computer software locates the liquid level and automatically processes collar reflections to accurately count almost all of the collars from the initial blast to the liquid level. This automatic analysis will determine the liquid level depth for 95% of the wells. However, some wells have conditions or anomalies that these procedures will not function as desired. This paper describes special advanced techniques that can be used to determine the liquid level in wells with these unusual conditions.

Slim hole completions have become quite common within the past six or seven years in both oil and gas wells. Lift design developments, some quite recent, have expanded the possibilities with this type of completion. The paper discusses advancements and practices in slim hole completions as related to sucker rod and subsurface hydraulic lift designs. It will be confined to designs applicable in casing diameters of 4 1/2" OD or smaller. Sucker rod designs will be those applicable in 2 3/8 " and 2 7/8" casing. Subsurface hydraulic designs will include 4 1/2 " OD casing.

Much of the emphasis in the oil industry today is associated with deeper drilling, offshore development and continued activity in the formation of large secondary recovery projects. With each of these trends, when artificial lift equipment is required, more than likely it will need to be capable of lifting greater volumes from greater depths. Manufacturers of hydraulic pumping equipment have been aware of this forthcoming need and have devoted much of their efforts during the past few years to the development of lift equipment capable of economically meeting these high horsepower needs. This paper will cover the developments in hydraulic pumping equipment in recent years as well as the preparation of maintenance and operating techniques which should make for improved hydraulic pumping installations and savings in operating expense.

Significant advances in hydraulic pumping will be reviewed, including a discussion of specialized applications of these improvements.

Deposits of paraffin wax, asphaltene, mineral scale and the water component of BS&W (basic sediments and water) in oil wells have cost producers millions of dollars in chemical, thermal and mechanical treatments, and in lost production. In some cases, traditional treatment methods have reduced the ability of the wells to produce to their potential. Previous treatment methods such as biological, galvanic, and magnetic devices were minimal and were limited to a few geographical areas. Ceramic or alnico magnets used in the past have been replaced by the introduction of new high energy product magnetic material, which is eight to thirty times more powerful. This new magnetic material has allowed more effective circuit design in magnetic fluid conditioners (MFCs). Performance of properly designed MFCs has greatly increased, resulting in more effective control of the deposition of solids in oil wells and associated equipment.

Since the decline in oil prices, the trend in the industry has been toward the maintenance of producing, existing reserves and away from the cost of trying to find new ones. The concern over the longevity of producing fields and new environmental legislation has led to an increased interest in corrosion control of downhole tubulars. If in situ complete and accurate measurements of downhole casing and tubing conditions can be made, the corrosion engineer can best determine the optimum cost-saving action to be taken. The consequences of not accurately evaluating the downhole condition relate to safety and environmental concerns, including blowouts and pollution, as well as loss of production. Recent developments have led to the introduction of several new tools specifically designed for the evaluation of casing and tubing deterioration. These new developments coupled with improvements to existing measurement systems now provide accurate techniques for interpreting the integrity of casing and tubing. The focus of this paper will be on the introduction and principles of measurement of this new technology. Resulting improved interpretation techniques will be demonstrated from actual field logs.

Dynamometer testing of sucker rod lifted wells is performed routinely in a safe and efficient manner throughout the world.

Dire predictions regarding the availability of petroleum and continuation of our present civilization, are indicated by the title of a recent presentation "The Peak of World Oil Production and the Road to the Olduvai Gorge," which predicts the crash of civilization in 2030." There are other more conservative predictions for just a peak in petroleum production in 2005. In a previous paper at this conference I projected the peak in oil production to 2040.

Field data on pumping well buildup curves illustrate long fluid column stabilization, U-tubing of liquid from tubing into the annulus, gas coning, high-pressure gas stringers, and high-pressure liquid stringers. Examples are given of truncation and of fitting two curves to the afterflow to get a better approximation of main pay and stringer properties, and of estimating unflooded stringer pressure from afterflow changes.

The American Gear Manufacturers' Association introduced its first recommendation for sizing oilfield pumping unit gear reducers in the year 1935. This recommendation eventually became AGMA Standard 422.02 and was incorporated in API Standard 11E. Since 1935 the only major change in API Standard 11E has been the addition of ductile iron as a gear material. AGMA's new standard, AGMA 422.XX, covers recommended gear ratings based on tooth strength as well as pitting resistance. The present standards, AGMA 422.02 and API llE, do not include specific recommendations for tooth strength. AGMA 422.XX also includes recommendations for sizing surface hardened gears in addition to thru hardened gears covered in the present standards. A detailed comparison between the new and old ratings, as well as the physical size of some typical oilfield pumping unit reducers, is illustrated and discussed.

Oil and gas drilling and production activities are currently regulated by many governmental entities. Such massive regulation inevitably leads to industry discussions concerning whether or not certain specific regulations are needed. This paper broadly outlines the impact of the Texas Clean Air Act of 1967 on petroleum drilling and production activities. The reasonableness and necessity of this act are reviewed with respect to the various petroleum-production activities.

This paper discusses the mechanics of air drilling, modifications such as mist or foam drilling, unique equipment requirements, and downhole problems that have been encountered. Special attention is given to describing techniques developed to prevent or control downhole problems.