A new clay stabilization system has been developed which prevents hydration of swellable clays without impairing permeability. The system uses a polymer that can be mixed in the HCI overflush of a typical mud acid treatment without loss of activity. Case histories proved the system to be very effective in controlling swelling clay problems.

Formation Damage resulting from the migration of small, mobile mineral particles within hydrocarbon producing formations has been, and continues to be a major concern of drilling and production engineers. The flow rate at which these small, usually colloidal, particles begin to dislodge and move within a formation is referred to as the critical flow rate. Many factors can influence the migration of fines within a producing formation: mineral composition, size and shape; pore throat size and distribution; relative fluid saturations; particle wettability; viscosity of the mobile fluid phase; fluid interfacial tension; production rate; and chemical alteration by drilling and completion fluids can affect the mobility of mineral species responsible for formation damage from in situ fines migration. A novel approach for the analysis and quantification of formation damage resulting from fines migration is described in this paper. The analysis is routinely performed on core plugs from whole core, rotary sidewall cores, and percussion sidewall cores. The technique described employs industry accepted practices for the measurement of single and multiphase permeability of core samples at reservoir conditions, as well as a novel experimental methodology and data processing technique for critical rate determination. A baseline permeability is established at a very low production rate. The rate is subsequently increased in a step wise fashion, returning to the established base rate after every consecutive rate increase. Experimentally derived flow rate and permeability data are converted to bottom hole and wellhead production rates using completion data and well geometry. The technique described in this paper is used successfully to augment production efforts in several producing formations by integrating the data obtained from flow studies with X-ray diffraction, scanning electron microscopy, and petrographic analysis. By imparting the ability to vary drilling and completion procedures while under simulated reservoir conditions in the laboratory, this analytical technique can reduce the risk of formation damage at all stages of well operations. Introduction The problem of permeability reduction resulting from the migration of in situ colloidal and detrital fines in petroleum reservoirs is a well documented phenomenon. Small, uncemented mineral particles, normally referred to as formation fines, exist in the pore networks of nearly all naturally permeable rock formations. These mineral particles vary considerably in composition and morphology. Fibrous or platy clay minerals often line the surfaces of pore cavities or bridge across the pore throats of sandstone and siltstone formations. These minerals are usually authigenic in nature, often forming in situ as a result of diagenetic alteration reactions of feldspathic and micaceous minerals within the rock. Small uncemented particles of quartz or calcite are usually also present in the pore spaces of most grainstone formations. When flow is initiated in a pore network containing loose or poorly attached solid particles, hydrodynamic conditions may reach a level at which these uncemented particles are subjected to forces large enough to dislodge and transport them through the porous medium. The flow rate at which fines migration begins is unique for every flow unit within a formation and, indeed, for every well and is referred to in this paper as the critical flow rate or critical production rate. P. 271^

Summary Several different types of materials have been evaluated for use in gravel packing high-temperature thermal wells. The materials include Ottawa sand, sand from Venezuela, resin-coated sand, sintered bauxite. and high-alumina beads. The materials were evaluated at various temperatums up to 600 deg. F (316 deg. C] and pH's ranging from 7.0 to 11.0. The tests were conducted by passing water in the fluid phase through samples of the various materials at the desired pH and temperature. Weight-loss measurements and visual inspection by a scanning electron microscope (SEM) were performed on each sample to determine the effect of the various temperatures and pH's. The steam evaluation of the various gravel-packing materials shows that the alumina-based materials are best suited for gravel packing thermal wells, where the temperature may reach 600 deg. F 1316 deg. C1 and the pH of the aqueous phase of the steam reaches 11.0. The alumina materials have very little weight loss and maintain a uniform shape. Quartz materials show dramatic weight losses as temperature and pH increase. The weight loss of resincoated sand is most affected by increasing pH al elevated temperatures. Introduction Steamflooding and stimulation by steam are two of the most widely used methods for the production of heavy crudes. Most thermal recovery operations are in formations that are classified as unconsolidated and that require some form of sand control. One accepted method of sand control is gravel packing the well with a highquality silica sand or other suitable materials, such as sintered bauxite or resin-coated sand. Shallow wells generally are stimulated with steam injection at moderate rates and temperatures under 450 deg. F [232 deg. C]. Deeper wells, however, may require steam at temperatures higher than 600 deg. F [316 deg. C to be injected at the wellhead. This high-temperature steam is required to ensure that enough heat is transmitted to the formation in the deep wells to allow for efficient recovery of the heavy crudes. It is well established that the solubility of quartz sand and other siliceous materials in water increases sharply at high temperatures and pH's (see Fig. 1). Because of the composition of certain feedwaters used for steam generation, the liquid phase of the injected steam can have a relatively high pH. Where high pH and high temperatures are observed, gravel packs composed of quartz sand can be relatively short-lived. Steam Evaluation of Gravel-Pack Materials Several different types of common gravel-pack materials were evaluated. Two sources of gravel-pack sand were tested to determine whether differences in quartz content were important to the stability of quartz at elevated pH and temperature. Ottawa sand, which contains 99.9% quartz, and a sand from Venezuela, which contains 95 % quartz and various amounts of impurities (such as feldspar goethic, kaolinite, chlorite, and illite), were as subjected to various temperatures up to 600 deg. F [316 deg. C and pH's up to 11.0. Two types of bauxitic materials were chosen for evaluation. The first material was the sintered bauxite commonly used as a high-strength fracture proppant. The second sintered-bauxite-type material is a byproduct of a manufacturing process and contains more A1203 than the more common fracture proppant. Table 1 shows a comparison of the properties of the two sintered materials. Sintered bauxite and high-alumina beads are very stable in high-temperature/dry-heat environments, as shown in Table 2. Terns at thermal-well conditions of temperature and pH were performed to determine whether the differences in the amount of A1203 of the two bauxitic materials would result in greater stability. The use of resin-coated sand to control sand in thermal wells has been growing in popularity over the past several years. Improvements in resin chemistry and manufacturing processes have helped to increase the thermal stability of this type of material and to prolong its effectiveness in the harsh environment of steam-recovery wells. Tests were performed to determine the stability of one such material as a function of pH and temperature. Effect of Feedwater Many of the waters used to produce steam for thermal recovery projects contain HCO-3. This material is found in the formation feedwater and is not removed during the softening treatment before injection into the steam generator. Thermal degradation of the HCO - ions in the feed-water results in CO2 and OH - . Because most steam generators in the field produce 80% steam, the OH ions remain dissolved in the aqueous phase of the steam and produce a very alkaline solution depending on the concentration of HCO - in the feedwater. JPT P. 2006^

Over the past few years, several premium sand-control screens have been introduced into the market. The proliferation of new screens has raised questions about how to choose the proper sand-control screen for a particular formation. To address this concern, a project was initiated at ChevronTexaco Exploration Production Technology Co. (EPTC) to devise a method to evaluate sand-control screens.As a result of this program, a method has been standardized for the evaluation of sand-control screens. The method, known as the screen efficiency (SE) test, shows the relationship between normalized sand-control characteristics (i.e., sand-control factor) of the screens and the normalized length of time it takes a screen to plug under a certain set of conditions (i.e., the performance factor). The results of SE tests to evaluate several sand-control screens for a North Sea and a west Africa field are discussed in the paper.The data in this paper also document that the numerical ratings given by the manufacturers are generally not very useful in understanding the sand-control rating of the particular screen or in comparing screens from different manufacturers. In addition, the effect of particle size distribution and sand concentration on the relative performance of sand-control screens was demonstrated by a comparison of SE plots of sands from the North Sea and west Africa fields.

The end of the millennium may hold significant difficulties for any system dependent on computer dates. Computers which misinterpret the year 2000 and other significant dates may require considerable repair. There have been many methodologies developed to assist companies with the process of Y2K repair. These methodologies and additional considerations for approaching Y2K solutions are presented. Specific measures to avoid logistics difficulties are discussed. The success of these measures can be considerably enhanced through the application of a transformation methodology. A proven transformation methodology for facilitating change is presented as applied to mitigating the Y2K risk.