A New Method for Sand Control and Well Stimulation in Unconsolidated Dirty Sands

Abstract

Abstract A new completion technique has been developed which allows unlimited drawdown and improves productivity in wells completed in unconsolidated productivity in wells completed in unconsolidated formations containing shales and clays. Historically, producing oil and gas from such reservoirs has been limited by rate-dependent sand production and fines migration which resulted in near wellbore formation plugging. This technique eliminates the problems of sand production and fines migration by problems of sand production and fines migration by artificially consolidating a volume of reservoir sand near the wellbore. The consolidation is resistant to high temperature, chemical attack, and degradation resulting from high velocity fluid flow. Additionally, porosity art permeability in the consolidated volume of reservoir sand are improved as a result of irreversible dehydration of clays. Introduction Sand control is essential to economic recovery of hydrocarbons from unconsolidated formations. Because of this, the development of sand control technology is ongoing within the industry. This paper presents a new technique known as the Solder paper presents a new technique known as the Solder Glass sand consolidation well completion method. The Solder Glass method is primarily an insitu consolidation technique. The sand consolidation which results from implementation of the technique is largely impervious to temperature and chemical attack, and is sufficiently resilient to withstand the high velocity fluid flow associated with good well productivity. In addition to the primary benefit of the technique, salient benefits primary benefit of the technique, salient benefits include an increase in porosity and permeability in the consolidated reservoir volume and stabilization of formation fines. These properties of Solder Glass sand consolidation make it particularly applicable to completions in unconsolidated particularly applicable to completions in unconsolidated reservoirs which are candidates for thermal recovery. Application of the Solder Glass well completion method has been concentrated in the Fruitvale Field A Kern County, California. Fruitvale is a typical California oil field. Its producing horizons consist of many thin, unconsolidated sand lenses alternated with often discontinuous shale streaks. Particle sizes within the oil bearing strata range from large rocks to the smallest of fines. The field was discovered in 1928, and initial completions with slotted liners flowed as high as one thousand barrels of oil per day. Production was curtailed in 1937 because of a poor market. Wide open production resumed during the high demand years of World War II. Subsequent water encroachment resulted in an unusually high decline rate in the relatively heavy oil reservoirs. As water production increased, sanding problems increased. Formation fines became entrained in the multiphase flow "' allowing particle movement. As sand was produced, cavities particle movement. As sand was produced, cavities were formed behind the pipe. Such cavities fostered casing failures and sloughing of the formation. Sand movement also allows reorganization of clay particles internal to the disturbed conglomerate with the ultimate result of formation plugging. Complete fluid shutoff in wells became a common occurrence. Backwashing, pressure washing, and sand-oil squeezing techniques were used to stimulate the plugged wells. Beneficial effects were, however, usually short lived. The need for repeated stimulation made such treatments economically unattractive. Reservoir pressures declined until wells would no longer flow. Artificial lift by means of rod pump became the dominant producing method. In high pump became the dominant producing method. In high water cut wells completed in natural water drive zones, producing rates had to be limited to prevent sanding. Consequently, many of the wells have been operated with extremely high fluid levels to control inflow velocities. Regardless, fines migration resulting in formation plugging and high pressure differential across perforations still occurs. pressure differential across perforations still occurs.