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For the past several years, foam has been used in many treatments as a fracturing fluid. Although many different types of reservoirs have been stimulated with foam, the primary zones of interest in Eastern Kentucky and Southern West Virginia have been the Berea Sandstone and the Devonian Shales. Due to the nature of these formations, i.e. low permeability, low bottom-hole pressure and water sensitivity, foam fracturing has been a successful technique.

Foam has been used successfully as a fracturing fluid as previously described by Blauer and Kohlhaas." They presented analytical measurements of fluid-loss coefficients and sand settling rates. Other investigator.9lo have discussed use of foam in other oilfield applications. Blauer, Mitchell and Kohlhaas" have reported rheological properties of foam. The physical structure of aqueous foams used for fracturing is used to explain foam viscosity and sand-supporting properties.

Dynamic laboratory testing of foamed acid on limestone cores has established the effectiveness of foamed acid as a stimulation fluid. The effects of foam quality, foam stability, and chemical. compatibility on fluid loss and fracture flow capacity were investigated. Recommendations are presented for deriving maximum benefits from a foamed acid treatment. Field results are presented that show the effectiveness of foamed acid in the stimulation of both oil and gas wells.

Foamed stimulation has been broadened to include the use of high- and low-quality (30% to 75% nitrogen) foams for acidizing soluble formations. To insure correct placement of foamed acidizing systems, foamed diverting techniques using high-quality (80% to 90% nitrogen) foamed water systems are currentIy being employed in several West Texas and Southeast New Mexico areas. Application of these techniques has been successful in both producing and injection wells. The mechanics of these systems will be discussed along with comparative results and current cost economics.

Foamed cement is a relatively new concept to oil/gas well completions. Foamed cement slurries produce good results provided several factors are considered. This paper will present several job design factors which help provide good results. It will also discuss several practices which should be avoided.

An infill drilling project was undertaken in the Eunice Monument South Unit (EMSU) to help balance the current water flood and strategically place producers and injectors into a smaller spacing and configuration. Past developments and treatments to better flood the units were initiated in 1996 to characterize the reservoir and improve the flood conformance. Knowledge gained led to the implementation of the infill drilling EMSU project and identified the criterias needed to offset the problems that would be faced.

Foamed hydrocarbons have been applied with great success in paraffin and heavy hydrocarbon penetration, foamed fracturing treatments, and fluid cleanout in wells in which hydrostatic pressure interferes with or completely stops gas production. Results of lab and field tests show this system to be effective as well as economical as an alternative in well treatment. He paraffin and heavy hydrocarbons removed in foamed aromatic hydrocarbons constituted up to 41 percent of the total volume of solids removed after a 1 hour shut-in period.

Market competition, shareholder returns, declining product price, technology, safety and environmental legislation continually challenge the oil and gas industry. An additional challenge faced by many oil and gas producers is effectively maintaining equipment to acceptable levels in order to sustain production targets. Asset reliability has become a focal point of discussion both domestically and internationally.

This paper describes an analytical procedure for forecasting the life expectancy of rock-bit journal bearings. Actual performance data and reliability analyses are used to establish empirical relationships and graphs that relate risk of bearing failure to operating parameters and drilling cost. The paper was originally published in SE Drilling Engineering, June 1990 (Volume 5, No. 2).

This paper describes an analytical procedure for forecasting the life expectancy of rock-bit journal bearings. Actual performance data and reliability analyses are used to establish empirical relationships and graphs that relate risk of bearing failure to operating parameters and drilling cost. The paper was originally published in SE Drilling Engineering, June 1990 (Volume 5, No. 2).

Paraffin and/or Asphaltenes, present in all oils/condensates, are responsible for damaging a majority of wells in the United States. Increasing production from these wells can be accomplished by removing the organic damage but the increase may be of short duration unless new damage is prevented. Squeeze treatments using paraffin and asphaltene inhibition chemicals have successfully held oil and gas production increases at elevated levels following stimulation by keeping new damage from reoccurring for greater than six months.

Sedimentary formations are the usual target for oil and gas exploration. Of the many classifications of these zones, carbonate and elastic deposits most often bear hydrocarbons in commercial quantities. Clastic formations are composed of broken and fragmented pieces of older existing rocks. Sands or sandstones can be classified as elastics. They result from erosion and weathering of land masses. The eroded particles are transported by various means to an area of deposition where they are laid down in somewhat orderly strata.

Information essential to interpretation of hydrocarbon and/or water productivity is not available from a single measurement technique, whether it be core analysis, complete suites of electrical logs or bottomhole pressure build-up or fall-off tests." The best features of each technique can be combined to obtain mutually consistent interpretations which result in improved evaluation of potentially productive intervals in a well. Methods are described which combine core analysis data with electrical resistivity logs.

Dehydration and of the proppant crushing inside the fracture, are the two damage mechanisms mostly recognized as the main contributors to the overall reduction in fractured well productivity. Fracture face damage caused by the fracturing fluid loss through the four fracture faces also creates additional pressure drop that may further reduce the effective wellbore radius. The magnitude of the effect depends on reservoir characteristics, fracture geometry, extent of fluid leakoff into the reservoir, and the viscosity of the fracturing fluid filtrate.

All types of machinery such as generators, process machinery, forges, machine tools, etc., are mounted on rigid and heavy foundations. The pumping unit is no more nor less than a piece of machinery designed in such a way and with suitable capacity to move a string of sucker rods up and down in a well thereby actuating the pump. In order for this machine to operate properly and give satisfactory service, it must be mounted on a suitable foundation.

Literature examples of the calculation of permeability and fracture length from the square root of time plot usually involve single phase flow. This paper discusses (1) fracture analysis based on multiple phase flow, (2) use of the slope of the linearity and the end of linearity for permeability and fracture length calculation, (3) what is the end of linearity and (4) problems in drawing the proper linearity in a square root of time plot.

The successful design and implementation of any improved oil recovery project in a fractured reservoir depends on an accurate characterization of the fracture system. This is especially true in a steam pilot project currently underway in the Yates Field of West Texas. This pilot will assess the economic viability of accelerating gravity drainage in the gas cap of the fractured San Andres reservoir. From the conceptual phase of the project through implementation and monitoring, fracture characterization in the pilot area has been critical to pilot design and success.

Natural fractures existing over a regional area have long been known to dominate all aspects of performance in the Spraberry Trend Area". However, there is little or no information on the actual fracture system other than: orientation, on a gross basis, from pulse and/or tracer tests in the 50's and 60"s, and fracture spacing inferred from simulation and a few existing vertical cores.

Passive seismic measurements were taken before, during, and after a fracture stimulation treatment to monitor the fracture growth and optimize future fracture treatments. The seismic events created by the fracture treatment showed an asymmetrical east-west trend during the treatment, with wide variations in the locations of events. The passive seismic measurements support the previous belief that the fracture orientation for the field is east-west. However, the recorded events showed more complexity to the fracturing process than had been anticipated.

A novel process has been developed to reduce the polymer damage associated with aqueous fracture treatments inclusive
of the filter cake and polymer residue and their detrimental effects to fracture conductivity, formation permeability,
and the resultant oil and gas production. This novel approach differs from conventional breaker applications in that the
formation is first treated with breakers and then the fracture treatment is performed.

In recent years several papers have been written on the merits of fracture stimulation with crosslinked methanol. While crosslinked methanol has been available to the industry since the late 1980"s, only in recent years has it been successfully and routinely utilized in the Permian Basin. This paper will discuss the fluid system, with focus on recent system refinements, while special attention will be paid to the development of standard procedures implemented to ensure methanol is pumped safely.

Approximately 20% of all fracture stimulation treatments in Conoco Inc.'s Odessa, Texas production area experienced problems which resulted in less than optimum frac jobs. Close examination of these treatments indicated that poor quality control was the primary reason for the problems experienced. To improve the quality control, guidelines were generated by engineering, field and service company personnel that 1) evaluates the service and safety performance of the treating company, 2) evaluates the design itself, and 3) discusses areas for improvement in subsequent jobs.

Multi-stage proppant fracture treatments are routinely applied to stimulate discrete formations and, more recently, distinct sections (stringers) within a formation to maximize the production of these finite zones. One method consists of perforating a zone, pumping a crosslinked pad, proppant-laden fluid; and acid followed by a gelled flush. A subsequent stage is then perforated, isolated and the process repeated. Multi-stage fracture treatments have been optimized by the use of highly efficient perforating techniques that perforate and isolate zones in less than 30 minutes.

This paper focuses on the various stimulation designs and treatments performed during the development of the Pecos Slope Field in eastern New Mexico. Information collected from over 125 wells has been categorized and studied in an attempt to determine the best possible stimulation technique for this formation. The Abo sand is a noncontinuous, lenticular, "tight gas" formation which has made evaluation of treatments difficult due to the manner in which these sands were deposited.

The theory of low fluid loss fracturing is presented. The fluid loss properties of current fracturing fluids are shown by a demonstration of the API test method. Fluid loss test results are interpreted in comparing fracturing fluids.