This report documents the drilling of a medium radius horizontal well in the Bartlesville Sand of the Flatrock Field, Osage County, Oklahoma by Rougeot Oil and Gas Corporation (Rougeot) of Sperry, Oklahoma. The report includes the rationale for selecting the particular site, the details of drilling the well, the production response, conclusions reached, and recommendations made for the future drilling of horizontal wells. 11 figs., 2 tabs.

Hydraulic fracturing is a common method employed to increase the production of oil and gas fields. Recently, there has been increased interest in monitoring the microearthquakes induced by hydraulic fracturing as a means of obtaining data to characterize reservoir changeS induced by the injection. Two types of microearthquakes have been observed during hydraulic fracturing. Tensile events have been observed and modeled as the parting of the surfaces of a fracture. A majority of the events observed have been shear-slip events, where two sides of a fault plane slip parallel to each other but in opposite directions. The locations of the microearthquakes can be analyzed to determine regions where significant seismic energy was released, which presumably are regions where injected fluid penetrated into the rock along pre-existing fractures or zones of weakness. The spatial patterns in the locations can be analyzed to fine regions where events cluster along planes, which are interpreted to be the dominant fluid flow paths. Imaging methods can also be applied to the travel time and waveform data to obtain direct evidence for the locations of the fractures or fracture zones. 27 refs., 2 figs.

A detailed understanding of rock structure and its influence on fluid entrapment, storage capacity, and flow behavior can improve the effective utilization and design of methods to increase the recovery of oil and gas from petroleum reservoirs. The dynamics of fluid flow and trapping phenomena in porous media was investigated. Miscible and immiscible displacement experiments in heterogeneous Berea and Shannon sandstone samples were monitored using X-ray computed tomography (CT scanning) to determine the effect of heterogeneities on fluid flow and trapping. The statistical analysis of pore and pore throat sizes in thin sections cut from these sandstone samples enabled the delineation of small-scale spatial distributions of porosity and permeability. Multiphase displacement experiments were conducted with micromodels constructed using thin slabs of the sandstones. The combination of the CT scanning, thin section, and micromodel techniques enables the investigation of how variations in pore characteristics influence fluid front advancement, fluid distributions, and fluid trapping. Plugs cut from the sandstone samples were investigated using high resolution nuclear magnetic resonance imaging permitting the visualization of oil, water or both within individual pores. The application of these insights will aid in the proper interpretation of relative permeability, capillary pressure, and electrical resistivity data obtained from …

This invention is comprised of an apparatus and method for simultaneously and separately emplacing two streams of different materials through a drillstring in a borehole to a downhole location for lost circulation control. The two streams are mixed outside the drillstring at the desired downhole location and harden only after mixing for control of a lost circulation zone.

The objective of this project is to perform a microbially enhanced oil recovery field pilot test in the Southeast Vassar Vertz Sand Unit (SEVVSU) in Payne County, Oklahoma. Indigenous, anaerobic, nitrate-reducing bacteria will be stimulated to selectively plug flow paths which have been preferentially swept by a prior waterflood. This will force future flood water to invade bypassed regions or the reservoir and increase sweep efficiency. Injection of nutrient stimulates the growth and metabolism of reservoir bacteria, which produces beneficial products to enhance oil recovery. Sometimes, chemical treatments are used to clean or condition injection water. Such a chemical treatment has been initiated by Sullivan and Company at the Southeast Vassar Vertz Sand Unit. The unit injection water was treated with a mixture of water, methanol, isopropyl alcohol, and three proprietary chemicals. To determine if the chemicals would have an impact on the pilot, it was important to determine the effects of the chemical additives on the growth and metabolism of the bacteria from wells in this field. Two types of media were used: a mineral salts medium with molasses and nitrate, and this medium with 25 ppm of the treatment chemicals added. Samples were collected anaerobically from each of …

Flow testing and heat extraction experiments in prototype Hot Dry Rock (HDR) geothermal reservoirs have uncovered several challenges which must be addressed before commercialization of the technology is possible. Foremost among these is the creation of a reservoir which simultaneously possesses high permeability pathways and a large volume of fractured rock. The current concept of heat extraction -- a steady state circulation system with fluid pumping from the injection well to a single, low pressure production well -- may limit our ability to create heat extraction systems which meet these goals. A single injection well feeding two production wells producing fluid at moderate pressures is shown to be a potentially superior way to extract heat. Cyclic production is also demonstrated to have potential as a method for sweeping fluid through a larger volume of rock, thereby inhibiting flow channeling and increasing reservoir lifetime. 10 refs., 4 figs., 2 tabs.

Each year the Geothermal Division of the US Department of Energy conducts an in-depth review of its entire geothermal R D program. The conference serves several purposes: a status report on current R D activities, an assessment of progress and problems, a review of management issues, and a technology transfer opportunity between DOE and the US geothermal community. This year's conference, Program Review IX, was held in San Francisco on March 19--21, 1991. The theme of this review was The Geothermal Partnership -- Industry, Utilities, and Government Meeting the Challenges of the 90's.'' The importance of this partnership has increased markedly as demands for improved technology must be balanced with available research resources. By working cooperatively, the geothermal community, including industry, utilities, DOE, and other state and federal agencies, can more effectively address common research needs. The challenge currently facing the geothermal partnership is to strengthen the bonds that ultimately will enhance opportunities for future development of geothermal resources. Program Review IX consisted of eight sessions including an opening session. The seven technical sessions included presentations by the relevant field researchers covering DOE-sponsored R D in hydrothermal, hot dry rock, and geopressured energy and the progress associated with the Long …

Production system design studies often include site-specific silica scaling field experiments, conducted because the onset and rate of scaling are believed difficult to predict, particularly at relatively low levels of oversaturation such as may exist in separators, flowlines, and injection wells. However, observed scaling occurrences (Cerro Prieto, Dixie Valley, Svartsengi, Otake, Hatchobaru, Milos, experimental work) actually conform fairly well to existing theory and rate equations. It should be possible to predict low level scaling with sufficient confidence for production and injection system design and, in cases where oversaturation is allowed, to design systems with foresight to suppress or manage the scale which develops. A promising suppression technology is fluid pH reduction by mixing with non-condensible gases and/or condensate. Calculations for injection lines at Uenotai geothermal field indicate molecular deposition at rates of 0.1 to 1 mm/yr, and some potential for particle deposition at points of turbulence, which can be suppressed by an order of magnitude with about 500 ppm CO{sub 2}. Further improvements of predictive technique will benefit from more uniformity in designing experiments, reporting results, and reporting measurements of scaling in actual production systems.

The objective of the cooperative research program is to characterize Alaskan reservoirs in terms of their reserves, physical and chemical properties, geologic configuration and structure, and the development potential. The tasks completed during this period include: (1) geologic reservoir description of Endicott Field; (2) petrographic characterization of core samples taken from selected stratigraphic horizons of the West Sak and Ugnu (Brookian) wells; (3) development of a polydispersed thermodynamic model for predicting asphaltene equilibria and asphaltene precipitation from crude oil-solvent mixtures, and (4) preliminary geologic description of the Milne Point Unit.

In the past two years, three very significant advances have been made in our understanding of the behavior and properties of Hot Dry Rock (HDR) geothermal reservoirs. First, we have determined that the rate of water loss from such deep, engineered reservoirs -- previously thought to be a major problem -- is minimal in the absence of reservoir growth, even under considerably elevated operating pressures. Second, a new method has been developed for determining the volume of hot fractured rock accessible to circulating water: i.e., the size of the HDR reservoir. This technique, after appropriate verification, will allow operators to actually quantify the size of the available thermal resource before power plant design and installation. Finally, the partitioning of reservoir fluid storage between the matrix microcracks and the network of joints has been measured at two pressure levels, one above and one below the joint opening pressure for the most favorably oriented set of joints. The observed difference in the storage partitioning above and below this threshold pressure is quite pronounced, particularly for the microcrack fraction. For any given HDR site, the measurement of this pressure-dependent storage partitioning may provide guidance as to the optimal method of reservoir production. 6 …

Detailed analysis and synthesis of geophysical, core, and hydrologic data from 230 wells were used to delineate the hydrostratigraphy and aquifer characteristics of the General Separations Area at SRS. The study area is hydrologically bounded on the north and northwest by Upper Three Runs Creek (UTRC) and on the south by Fourmile Branch (FB). The Cretaceous-Tertiary sedimentary sequence underlying the study area is divided into two Aquifer Systems; in ascending order, Aquifer Systems I and 11. The study concentrated on Aquifer System U, which includes all the Tertiary sediments above the Black Mingo Group (Paleocene) to the water table. This report includes a series of lithostratigraphic cross-sections, piezometric gradient profiles, head ratio contour maps, aquifer isopach maps, and potentiometric surface maps which illustrate the aquifer characteristics of the study area.

Mt. Pinatubo is one of several recent-age volcanoes along the west Luzon volcanic arc. A fumarole near the suminit emits gases with magmatic characteristics. Several thermal springs on the east and west flanks yield various fluid typos, including neutral chloride and bicarbonate. Three wellbores probed the Mt. Pinatubo caldera from elevations of +1230 through -1600 mRSL. Trajectories may be described as: central, crossing a boundary wall from the inside, and skirting a wall [probably] on the inside. Brine discharges indicate severe evapo-concentration effects accompanied by other phenomena. Severity of evapo-concentration indicates low fluid mobility near the wellbores. Large variations for ratios of component concentrations were observed, indicating negligible natural circulation (mixing). Implications about fluid movements and heat transfer processes are explored. Three components of steam can be quantified and all are significant: separate entry, adiabatic boiling, and boiling by rock heat.

Acid chloride corrosion of geothermal well casings, production piping and power plant equipment has resulted in costly corrosion damage, frequent curtailments of power plants and the permanent shut-in of wells in certain areas of The Geysers. Techniques have been developed to mitigate these corrosion problems, allowing continued production of steam from high chloride wells with minimal impact on production and power generation facilities.The optimization of water and caustic steam scrubbing, steam/liquid separation and process fluid chemistry has led to effective and reliable corrosion mitigation systems currently in routine use at The Geysers. When properly operated, these systems can yield steam purities equal to or greater than those encountered in areas of The Geysers where chloride corrosion is not a problem. Developments in corrosion monitoring techniques, steam sampling and analytical methodologies for trace impurities, and computer modeling of the fluid chemistry has been instrumental in the success of this technology.

Lost circulation is the loss of drilling fluid from the wellbore to fractures or pores in the rock formation. In geothermal drilling, lost circulation is often a serious problem that contributes greatly to the cost of the average geothermal well. The Lost Circulation Technology Development Program is sponsored at Sandia National Laboratories by the US Department of Energy. The goal of the program is to reduce lost circulation costs by 30--50{percent} through the development of mitigation and characterization technology. This paper describes the technical progress made in this program during the period April, 1990--March, 1991. 4 refs., 15 figs., 1 tab.

This is the ninth annual edition of the Energy Information Administration's (EIA) Oil and Gas Field Code Master List. It reflects data collected through October 1990 and provides standardized field name spellings and codes for all identified oil and/or gas fields in the United States. There are 54,963 field records in this year's Oil and Gas Field Code Master List (FCML). This amounts to 467 more than in last year's report. As it is maintained by EIA, the Master List includes: Field records for each state and county in which a field resides; field records for each offshore area block in the Gulf of Mexico in which a field resides;field records for each alias field name; fields crossing state boundaries that may be assigned different names by the respective state naming authorities.

The Geothermal Direct Use Engineering and Design Guidebook is designed to be a comprehensive, thoroughly practical reference guide for engineers and designers of direct heat projects. These projects could include the conversion of geothermal energy into space heating and cooling of buildings, district heating, greenhouse heating, aquaculture and industrial processing. The Guidebook is directed at understanding the nature of geothermal resources and the exploration of the resources, fluid sampling techniques, drilling, and completion of geothermal wells through well testing, and reservoir evaluation. It presents information useful to engineers on the specification of equipment including well pumps, piping, heat exchangers, space heating equipment, heat pumps and absorption refrigeration. A compilation of current information about greenhouse aquaculture and industrial applications is included together with a discussion of engineering cost analysis, regulation requirements, and environmental consideration. The purpose of the Guidebook is to provide an integrated view for the development of direct use projects for which there is a very large potential in the United States.

The objectives of this research are to: (1) assist producers in locating and producing petroleum not currently produced because of technological problems or the inability to identify details of reservoir compartmentalization, (2) to decrease risk in field development, and (3) accelerate the retrieval and analysis of baseline geoscience information for initial reservoir description. The interdisciplinary data sought in this research will be used to resolve specific problems in correlation of strata and to establish the mechanisms responsible for the Upper Pennsylvanian stratigraphic architecture in the Midcontinent. The data will better constrain ancillary problems related to the validation of depositional sequence and subsequence correlation, subsidence patterns, sedimentation rates, sea-level changes, and the relationship of sedimentary sequences to basement terrains. The geoscientific information, including data from field studies, surface and near-surface reservoir analogues, and regional database development, will also be used for development of geologic computer process-based simulation models tailored to specific depositional sequences for use in improving prediction of reservoir characteristics. 4 refs.

Detailed analysis and synthesis of geophysical, core, and hydrologic data from 230 wells were used to delineate the hydrostratigraphy and aquifer characteristics of the General Separations Area at SRS. The study area is hydrologically bounded on the north and northwest by Upper Three Runs Creek (UTRC) and on the south by Fourmile Branch (FB). The Cretaceous-Tertiary sedimentary sequence underlying the study area is divided into two Aquifer Systems; in ascending order, Aquifer Systems I and 11. The study concentrated on Aquifer System U, which includes all the Tertiary sediments above the Black Mingo Group (Paleocene) to the water table. This report includes a series of lithostratigraphic cross-sections, piezometric gradient profiles, head ratio contour maps, aquifer isopach maps, and potentiometric surface maps which illustrate the aquifer characteristics of the study area.

The purpose of the study was to systematically identify and review (a) the known and undiscovered reserves and resources of arctic Alaska, (b) the economic factors controlling development, (c) the risks and environmental considerations involved in development, and (d) the impacts of a temporary shutdown of the Alaska North Slope Oil Delivery System (ANSODS). 119 refs., 45 figs., 41 tabs.

Research in progress to evaluate natural, igenous-related hydrothermal fracturing as a reservoir control in two eastern Nevada oil fields has revealed evidence of a far more comprehensive role for moderate- to high-temperature hydrothermal systems in Basin-and-Range oil-reservoir evolution. Fluid-inclusion and petrographic studies have shown that (now) oil-bearing dolomite breccias of the Blackburn field (Pine Valley, Eureka County) were formed when overpressured, magmatically-heated, high-temperature (>350{degrees}C) hydrothermal brines explosively ruptured their host rocks; similar studies of texturally identical breccias of the Grant Canyon/Bacon Flat field (Railroad Valley, Nye County) so far do not support such an explosive origin. At Grant Canyon, however, hydrothermal, breccia-cementing quartz hosts primary oil, aqueous/oil, and aqueous fluid inclusions (homogenization temperature = 120{degrees}C) which document a direct geothermal connection for oil migration and entrapment. Moreover, at both Blackburn and Grant Canyon/Bacon Flat, the oil reservoirs are top- and side-sealed by hydrothermally altered Tertiary ignimbrites and epiclastic rocks. Contemporary geothermal activity is also apparent at grant Canyon/Bacon Flat, where subsurface water temperatures reach 171{degrees}C, and at Blackburn, above which a petroleum-providing hot spring issues at a temperature of 90{degrees}C. We suggest that in the Basin and Range province, hydrothermal systems may have: (1) matured oil from otherwise submature source …

This report describes environmental activities conducted on and in the vicinity of the Savannah River Site (SRS) in Aiken, S.C., from Jan. 1 to Dec. 31, 1991, with an update on compliance activities through April 1, 1992. The report is a single volume with a separate summary pamphlet highlighting the major findings for 1991. The report is divided into an executive summary and 14 chapters containing information on environmental compliance issues, environmental monitoring methods and programs, and environmental research activities for 1991, as well as historical data from previous years. Analytical results, figures, charts, and data tables relevant to the environmental monitoring program for 1991 at SRS are included.

The Clearlake Project is a three-party collaboration between the California Energy Commission, City of Clearlake, and Los Alamos National Laboratory. It aims to develop a deep hot, dry geothermal resource under the city. The project is funded by the Commission, and administered by the City. Technical operations are conducted by Laboratory staff and resources seconded from the Hot Dry Rock program. In addition to the normal geothermal exploration problems of predicting geological and geophysical properties of the subsurface, there are uncertainties as to what further material and environmental parameters are relevant, and how they might be measured. In addition to technical factors, policy objectives are an influence in choosing the most appropriate development scenario. 11 refs., 4 figs.

The Nagqu geothermal field is a single-phase, liquid-dominated system at reservoir conditions, having a high gas content. This field is located at an elevation of about 4,500 m (asl), in the vicinity of the City of Nagqu, which is one of the most important cities of Tibet.The reservoir rock is made of a highly fractured, low-permeability sedimentary sequence. During the implementation of the study described in this paper, fluid production was mainly obtained from two out of four possible productive wells. The main fault systems are located in a NE-SW and E-W directions, which seem to control fluid movement at depth. The geothermal field is restricted to a small area where hydrothermal manifestations are located. Reservoir temperature is 114 C, gas content is in the range of 0.5 to 0.6% by mass, being mainly CO{sub 2}. Reservoir transmissivity in the area of the wells is very high. Reservoir response to changes in flow rate in any of the producing wells could be detected almost immediately in the observation wells, which were distant between 300 to 900 m, depending on the production-observation well arrangement. Calcium carbonate scaling was present in all producing wells. This deposition was controlled by the CO{sub 2} …

A conceptual geologic model of the Roosevelt Hot Springs hydrothermal system was developed by a review of the available literature. The hydrothermal system consists of a meteoric recharge area in the Mineral Mountains, fluid circulation paths to depth, a heat source, and an outflow plume. A conceptual model based on the available data can be simulated in the native state using parameters that fall within observed ranges. The model temperatures, recharge rates, and fluid travel times are sensitive to the permeability in the Mineral Mountains. The simulation results suggests the presence of a magma chamber at depth as the likely heat source. A two-dimensional study of the hydrothermal system can be used to establish boundary conditions for further study of the geothermal reservoir.