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In-fill development within mature producing fields has been increasing throughout the Permian Basin, West Texas. Stimulation of new wells and recompletion of present producers and injectors many times accompanies this in-fill development. Most recent studies have focused on the overall strategy of in-fill development from a petrophysical characterization standpoint. The impact of hydraulic fracturing within a secondary recovery project has not been as thoroughly investigated as to benefits in production enhancement and overall field development.

Several studies have appeared in the literature concerning details of dynamic models of beam pump and rod string performance. Many of these studies deal with the equations and models presented by S. G. Gibbs.*-" Also, some other work has indicated techniques of modeling and solutions to governing equations. An equation is developed here which is used to generate a "diagnostic" and a "design" type of beam pump analysis program. The equations needed at the interface of rods of different properties are presented and discussed.

Fluid viscosity reduction is commonly used to gauge polymer degradation. Although viscosity reduction indicates polymer degradation, it is misleading to conclude that this reduced viscosity equates to improved fracture conductivity. Polymer fragments which are desolubilized from the gelled fluid no longer contribute to fluid viscosity but do, unfortunately, contribute significantly to proppant pack damage. Several new breaker technologies have been introduced in efforts to improve polymer degradation, and thereby, improve fracture conductivity and ultimately, well productivity.

Shell Exploration & Production Company is currently utilizing capillary injection systems to deliver corrosion inhibition chemicals in several gas wells in their South Texas fields. Traditional methods to handle corrosive production wellbores has been to treat? Corrosion Resistant Alloys (CRA"s) or periodic batch treatments with corrosion inhibition chemicals. The installation of CRA materials has been the preferred method especially in the more corrosive environments, but the high cost of these materials can be prohibitive in some installations.

The transport of propping agent particles through the perforations, down the perforation tunnels, and into the fracture via the crosscut channels connecting the perforating tunnels and the fracture present special flow problems during hydraulic fracturing operations. Hydraulic fracturing treatments are commonly performed in the field, yet surprisingly little experimental or analytical work is available to guide engineers in selecting operating conditions to ensure that propping agent particles are transported efficiently from the casing into the fracture.

The transport of propping agent particles through the perforations, down the perforation tunnels, and into the fracture via the crosscut channels connecting the perforating tunnels and the fracture present special flow problems during hydraulic fracturing operations. Hydraulic fracturing treatments are commonly performed in the field, yet surprisingly little experimental or analytical work is available to guide engineers in selecting operating conditions to ensure that propping agent particles are transported efficiently from the casing into the fracture.

The brine external polymulsion acid fracturing technique has been successfully utilized by Exxon to stimulate the low permeability carbonate reservoirs of the Permian Basin. Compared to the traditional proppant fracturing methods, this approach offers the advantages of lower cost, reduced mechanical risk, and greater adaptability to difficult well situations. Polymulsion is an external aqueous-phase oil-water emulsion. The non-Newtonian properties of this emulsion create an efficient fracturing fluid which exhibits excellent pumping characteristics.

A new technology is available that provides a more accurate and dependable method of opening a valve to relieve pressure, closing a valve to isolate pressure, or switching a valve to divert pressure. An expendable pin (the buckling pin) obeying Euler's Law acts both as a sensor and valve actuator to open, close, or divert valves at an exact set pressure.

The Bull Dog@ Bailer (Patent No. 4,493,383) offers a method to clean out sand and debris from the wellbore or casing without loading the hole and circulating. The bailer tool assembly consists of a bottom hole tool, float valve, cavity as per weight chart, and the Bull Dog@ Bailer. The tool must be run in fluid, so cavity length cannot exceed the column. Reciprocation (5 ft. stroke) of the pump assembly draws fluid and sand in through the bottom hole tool, through the float valve, and up into the cavity tubing chamber.

The oil industry typically selects perforators based on published performance specifications. Depth 01

Early applications for butterfly valves were restricted to throttling control in many types of fluid flow systems. These early throttling-type butterfly valves were very similar to the disc in an automobile carburetor and did not provide positive shutoff. In the early part of this century, however, semipositive low-pressure shutoff butterfly valves were developed, using natural rubber for seating materials.

Whenever large volumes of oil-well fluid have to be lifted, the submersible pump-motor system is the most logical artificial lift system to use. The submersible pump will operate efficiently above 300 barrels per day. The submersible pumping system is composed of the motor, seal, pump, and other hardware, as well as a long length of power cable. The most obvious unique feature of a submersible system is its geometry to fit a narrow hole and its reliability to last under adverse environmental conditions without convenient access for repair or inspection.

ESP cable is an integral part of the submersible pumping system. Operating cost considerations have moved the industry towards re-use of equipment. Testing of submersible pumps, motors, seal sections and gas separators is currently being conducted by all major manufacturers of ESP equipment. A normal progression would require that ESP Cables follow the same suit. Many users currently rely on a 1000 Volt megohmmeter or a DC Hi-Pot test to determine if a cable is suitable for re-use.

A significant available resource of unrecovered mobile oil resides within Grayburg reservoirs as a result of low ultimate recoveries of less than 30 percent of the large estimated volume of original oil in place. This low ultimate recovery from conventional primary and secondary recovery methods is due mainly to the heterogeneity typical of these reservoirs. Evidence of this heterogeneity is well displayed in the Dune field by significant production inequalities, particularly within the Mobil University Unit 15/16.

Inflatable impression packers are not new; they have been around for a number of years.1"2"3 However, their use has been very limited, probably due to one or more of the following limitations: 1. High differential pressure was required to squeeze impressionable material into cracks or perforations, which necessitated an inflatable packer which was expensive to manufacture and difficult to make longer than about 10 feet. 2. The inflation pressure often had to be held for up to 10 hours in order to be able to retain an impression. 3.

The unprecedented rile in the cost of tublar goods has made operators look for cost-effective ways to extend tubing life. Fasken has found that using poly lined tubing in rod pumped, injection and disposal wells has been a good option in reducing well failures as well as extending tubing life. Installing a poly liner over damaged IPC tubing is one example of using this liner system and has also been successful in several other applications.

For the past few years there has been a lot of effort expended on examining potential electrical cost savings in the oil field. This paper presents efforts to examine the electrical savings in rod pumping operations by: 1. Motor changes and downsizing 2. Reversing the direction of rotation 3. Changing well operation run times and frequency 4. The effect of installing a down hole gas separator All of these operational changes are inexpensive and the electrical cost savings compared to cost of making the changes are discussed.

From its first development in the early 1960's an effort has been made to optimize a stimulation procedure for the Canyon Sand formation in Southwest Texas. Many attempts have been made to find a fluid system that would maximize stimulation results while minimizing treatment cost and formation damage. As a result, a variety of fluid systems have been pumped consisting of a wide range of both fluid and proppant volumes. This paper investigates historic stimulation practices over eight selected study areas.

There are various oil and gas fields across the United States that have been producing for over 100 plus years.

Carbon dioxide corrosion studies of oil-well portland cements were initiated using a new microsample technique to determine the effect of carbonic acid on portland cement slurry formulations and to develop a high carbonic acid corrosion-resistant cement for carbon dioxide Enhanced Oil Recovery applications. Earlier results from studies using two-inch API cement cubes showed carbonic acid had essentially no effect on cement after relative short test periods at elevated temperatures. Similar results with two-inch API cement cubes also were reported in recent literature.

Carbonate formations are predominate in the Permian Basin and as such are commonly stimulated with acids. Success of an acid treatment is dependent on knowledge of the reservoir, design techniques and execution; and emphasis on obtaining good zone coverage. Case histories of acid stimulation, with production results, are presented covering San Andres and Devonian horizontal wells and deep hot Ellenburger wells. Treatments varied from high rate matrix to hydraulic fracturing operations.

Carbonated waterflooding is an enhanced oil recovery process developed in the early 1950's that may have potential application in several West Texas reservoirs. The process consists of saturating injection water with CO, in order to swell the remaining oil-in-place, and thereby increase the amount of recoverable oil in a reservoir. The process usually involves less investment and CO, demand than miscible CO, flooding.

Shortages of drill pipe have hit the industry hard for the past few years. Not only has there been a lack of availability of pipe, but costs to replace discarded strings and strings for new rigs have risen sharply. Therefore, the subject of proper care and handling of drill stems becomes increasingly more important. Owners and users must get maximum life with a minimum of problems for their drill strings. Much has been done to increase the life of drill strings, but much more can be accomplished with a broader understanding and practical approach to proper care of drill stems.

The sucker rod manufacturers are fully cognizant of the fact that sucker rods are required to fulfill one of the most stringent tasks that is offered by today's petroleum producing program. In an effort to combat this challenge the industry has solicited the full support of this nation's great metallurgical research capacity. However, basic steel and steel alloys are merely the initial step toward an end, and the responsibility of providing the necessary medium is entirely the responsibility of the manufacturer, and the degree of responsibility lies with each individual manufacturer.

Manufacturers attempt to deliver sucker rods to the user in the same condition as when they left mill. The processes of unloading, storage, and transportation to the field must be just as carefully carried out, since carelessness at any of these stages can nullify the efforts made at any other stage.