Deepwater Wells Research Articles

A National Evaluation of the Leaching Potential of Aldicarb Part 2. An Evaluation of Ground Water Monitoring Data

AbstractAldicarb was first found in ground water in Suffolk County, New York, in the late 1970s associated with its use on potatoes. Since then, there has been a substantial amount of monitoring associated with aldicarb use on potatoes nationally and on citrus in Florida. A recent monitoring study by the registrant of aldicarb supplemented limited monitoring data on other critical aldicarb uses including cotton and peanuts. This paper reports on monitoring programs and studies encompassing more than 50,000 ground water samples, of which approximately 32 percent are positive and 13 percent are above EPA's Health Advisory Level of 10 ppb. These monitoring results were used in an integrated assessment to identify areas of the United States where aldicarb is likely to leach to ground water (Lorber et al. 1989). Positive findings are reported for 61 counties in 19 states, and findings above 10 ppb are reported for 31 counties in 11 states. Monitoring data associated with the use of aldicarb on potatoes in the Northeast and upper Midwest (Wisconsin, Virginia, New York, Massachusetts, Rhode Island, Maine) are extensive and demonstrate the potential for aldicarb to impact ground water near potato‐use sites. In contrast, monitoring associated with potato use in the Northwest (Idaho, Oregon, Washington) and a three‐county potato‐growing area in Florida have shown negative results. Sampling near cotton use in the South and Southwest (Georgia, Alabama, Tennessee, Arkansa, Louisiana, Texas, Arizona) showed negative findings, while a small number of positives were found in North Carolina and South Carolina. Limited monitoring associated with peanuts showed negative results in the South (North Carolina, South Carolina, Georgia), although sampling beneath a field research site in Georgia showed trace positives. Sampling from monitoring wells established in the shallow water table aquifer beneath and downgradient from citrus use sites in Florida showed both a high frequency and high concentrations of aldicarb, with one finding above 1000 ppb and numerous findings greater than 100 ppb. However, in three separate efforts encompassing more than 1200 samples from roughly the same number of domestic drinking water wells located near citrus fields with histories of aldicarb usage, only 2 percent contained residues of aldicarb. No positives were found in 800 samples from roughly the same number of deep public drinking water wells in counties with high citrus acreage and aldicarb usage. This paper also reports on monitoring associated with lily bulb use in northern California, fernery use in Florida, sugar beet use in Montana, and smaller exploratory efforts in several other states.

Subsea Adjustable Choke Valves: A Focus on a Critical Component

Summary With emphasis on deepwater wells and marginal offshore fields growing, the search for reliable subsea production systems has become a high priority. A reliable subsea adjustable choke is essential to the realization of such a system, and recent advances are producing the degree of reliability required. Technological developments have been primarily in (1) trim material (including polycrystalline diamond), (2) trim configuration, (3) computer programs for trim sizing, (4) component materials, and (5) diver/remote-operated-vehicle (ROV) interfaces. These five facets are overviewed and progress to date is reported. A 15- to 20-year service life for adjustable subsea chokes is now a reality. Another factor vital to efficient use of these technological developments is to involve the choke manufacturer and ROV/diver personnel in initial system conceptualization. In this manner, maximum benefit can be derived from the latest technology. Major areas of development still required and under way are listed, and the paper closes with a tabulation of successful subsea choke installations in recent years.

Formation of Hydrates During Deepwater Drilling Operations

Two deepwater wells in widely separated geographical areas have experienced natural gas hydrate information during drilling operations. In both cases, hydrates, ice-like mixtures of natural gas and water, plugged subsea equipment, causing difficulties in subsequent operations. The potential for hydrate formation merits consideration during planning and conducting of deepwater drilling operations.

The Automatic Well Temperature Measuring System Installed At Cape Allison C-47, Offshore Well, Arctic Islands Of Canada. Part 2 - Data Retrieval And Analysis Of The Thermal Regime

Abstract Precise well temperatures to 800 m below the seabed have been obtained with an automated data acquisition system from an offshore well, Canadian Arctic Islands. Temperatures show the cooling of the well following the drilling and testing phase, Analysis of the data has characterized the geothermal regime for the region. The deep temperatures appear to be in thermal equilibrium, in contrast to temperatures at many onshore wells that are in disequilibrium because of the influence of recent marine regression and climatic change. The terrestrial heat flow calculated from this data is 39 mWm-2; uncertainty in thermal conductivity suggests it may be somewhat higher, probably not exceeding 52 mWm-2. This range is supported by calculations using bottomhole and drill-stem test temperatures from deeper in the well, These results suggest a low to moderate terrestrial heat flow for the Sverdrup Basin. The analysis has demonstrated the anisotropy of shale with respect to thermal conductivity, and has clarified the interpretation 0/ the onshore geothermal regime. Introduction Bottom-hole temperatures (BRT) obtained during geophysical well logging, and temperatures measured during drill-stem tests (DST) afford the opportunity of reconstructing the ground thermal regime(l). Such data have been used, for instance, to predict well performance(2) and to determine the underlying thermal history for petroleum maturation studies(3). However, temperatures and other parameters may be disturbed at this time, and may not represent the undisturbed state, despite the application of corrections(4). In addition, such data do not afford the opportunity of studying long-term changes. To overcome some of these limitations and to establish a data base of precision ground temperatures and permafrost thicknesses, temperature measurements up to 1000 m have been made at some 130 onshore petroleum exploration wells in the Canadian Arctic for periods of up to 20 years(5, 6). Figure 1 (right half) illustrates two methods used to acquire the data. A challenge, however, has been to obtain ground temperature information from offshore areas comparable to that more readily obtained at these onshore wells; this is particularly crucial in the Canadian Arctic for two principal reasons. First, hundreds of metres of ice-bonded permafrost underlie the Beaufort Sea and no precision deep temperature data exists at present(7). Second, in the Queen Elizabeth Islands (Fig. 2), for example, ground temperatures at onshore wells reflect a complicated history of climatic change and marine regression; the offshore thermal regime, where transient environmental effects are minimal, may hold a key to the reconciliation of the o:pshore temperatures and to the wide variation recorded in onshore permafrost thicknesses(6) (Fig, 3). Recently, precise temperatures from a deep-water offshore well in the Queen Elizabeth Islands have been obtained to provide some insight into these problems. The novel method of installing an 800 m multithermistor cable and automatic temperature logging system in this well, Panarctic et al, Cape Allison C-47 (No. 427 in Fig. 3), is described in a preceding paper(8); the configuration is shown in the left half of Figure 1.

Logging in deep water wells in central Jutland, Denmark

During a search for unpolluted resources, new wells have been drilled to a deep confined aquifer in central Jutland. Since little is known about the extent and vulnerability of the deep reservoir, geophysical logging was used to supplement hydraulic well‐testing. Gamma‐ray, SP and resistivity logs were recorded in the boreholes. Gamma‐logs were also recorded in two cased wells. Analysis of the logs, combined with information from samples, shows an unconfined aquifer of quartz and mica sand to a depth of about 55 m at Grindsted. Below this level there is a 40 m thick aquitard with an apparent southerly dip. The aquitard is composed of interbedded sand, silt and clay. The deep confined aquifer extends from 95 to 110 m below the surface at Grindsted. Both the aquitard and the deep aquifer are provisionally dated as Early/Middle Miocene. The electrical logs discriminate well between sand, silt and clay beds. If a suitable mud is used in the well it is possible to calculate the formation water resistivities in good agreement with water samples obtained after completion. From the resistivity logs formation factors were calculated in the range 3–5 using no‐invasion departure curves. The high content of heavy mineralsin the Tertiary deposits makes it impossible to obtain precise lithological information from the gamma‐ray log. On the other hand this log provides clear markers for identifying the hydrogeological units in the well‐bores.

Isotope Chronostratigraphy: High-Resolution Stratigraphic Correlations in Deep-Water Exploration Tracts of Northern Gulf of Mexico: ABSTRACT

ABSTRACT On-going stable isotope research with cuttings from over 16 Plio-Pleistocene deep-water wells has established a high-resolution framework for chronostratigraphic tie-lines between Plio-Pleistocene wells. Detailed oxygen isotope (O-18/O-16) records from core material and sixteen exploration wells at 30 intervals provide a large data base by which to establish a chemical stratigraphy record for the Gulf of Mexico. This type section is used to evaluate the stratigraphic integrity of exploration wells and the timing and reliability of important calcareous nannofossil and foraminiferal biostratigraphic datums. Within this framework, freshwater discharge events and local/regional unconformities can be defined with high precision. The record can be used to relate large-scale and fine-scale changes in 1) sediment accumulation rates, 2) the distribution of sand-shale facies, and 3) seismic sequence boundaries of glacio-eustatic cycles. Integration of this information can lead to a more precise definition of the timing and extent of target sand bodies in deep-water exploration tracts.

Simulation and performance analysis of floating drilling rig operations

A computer program that can run on a personal computer was developed to simulate a sequence of drilling tasks such as the drilling and completion of deep water wells. The program can be used for techno- economic evaluations of different vessels competing for the same drill job. It can also be used for long term planning for drill jobs to be carried out at different locations and in different seasons. The simulation has two parts. The first simulates sea states, making use of the Markov approach. The second simulates drill operations. Rig motions are determined by the sea states and compared against operational limits. Work is slowed down or interrupted when limits are exceeded.

Aquifer Classification for the UIC Program: Prototype Studies in New Mexico

ABSTRACTThree case studies from New Mexico illustrate methods by which aquifers can be classified for purposes of the Federal Underground Injection Control program. The principal technique involves preparation of hydrogeologic maps or cross sections which display information on the permeability of rock units and the dissolved solids content of formation fluids. Because deep water wells are lacking in most areas, the analysis normally requires considerable interpretation of geological and geophysical logs collected by energy and mineral companies, plus use of a general model or concept about regional hydrogeology. Injection of waste fluids into aquifers containing water with less than 10,000 mg/1 dissolved solids is not allowed unless an exemption is justified by economic, engineering and other factors. Based on the case studies, regulatory exemptions will be possible for aquifers which are hydrocarbon or mineral‐producing, or which are important for brine disposal purposes.

Use of Vertical and Surface Seismic Profiles to Investigate Distribution of Aquifers in Madison Group and Red River Formation, Powder River Basin, Wyoming-Montana: ABSTRACT

Intensive energy development activity in the Powder River basin area of eastern Wyoming has placed heavy demands on the limited water resources of the state. Water cannot be obtained from streams, rivers, or shallow wells to support coal-slurry pipelines, coal gasification, shale retorting, or even in many places enlarged municipal water systems. The U.S. Geological Survey is, therefore, promoting the water resource potential of the Madison Group and Red River Formation. Such water is to be produced from depths of 2,500 to 7,500 ft (762 to 2,286 m) to supply some of the needs cited. Because deep water wells are expensive, and Madison-Red River productivity varies drastically throughout the area, it is highly desirable to select drilling sites with a high probability of good water production. The exploration seismograph is a promising tool to aid in site selection. The object of the investigation was to determine under what conditions the exploration seismograph can be used to detect porosity development at depth in the horizons of interest, an application which also has obvious significance to the petroleum industry. In-situ measurements of the acoustic properties of the Madison-Red River interval have been made using vertical seismic profiles in several wells. Surface seismic profiles were then run over the wells in which vertical seismic profiles had been made. The combination of these results, together with well log data and regional geologic subsurface studies, give one considerable insight into the problem of exploring for commercial quantities of water at depth. End_of_Article - Last_Page 894------------

Hazards of Waste Disposal in Groundwater Basins: ABSTRACT

As problems of waste disposal become more critical, and environmental constraints more demanding, serious consideration is being given to isolated zones in groundwater basins as burial grounds for hazardous wastes. Proponents have suggested various geologic environments--thick impermeable clay or shale layers, heavily pumped subsidence basins, deep saline water bodies, etc.--as being safe disposal sites. However, several hydrogeologic constraints must be understood fully before a prospective site can be considered isolated. Unconsolidated deposits, even at great depth, are highly sensitive to changes in applied stress. Interstitial fluids may be squeezed from even relatively impermeable beds by modest stress changes. Compaction of the deposits below 2,500 ft has been induced in the San Joaquin Valley by groundwater pumping. As much as 30 ft of vertical shortening in 3,000 ft of water-bearing deposits has been measured. At Alpaugh, more than 4 ft of surface subsidence, principally due to the compaction of fine-grained beds at depth, has resulted from 250 ft of artesian head decline. Interstitial arsenic, presumably locked in clay interbeds for thousands of years of interaquifer circulation, now is being squeezed into the aquifers. Hydraulic stresses in a developing groundwater basin may affect beds considerably below the deepest pumping wells. Theoretically, seepage stresses, and thereby groundwater movement, ultimately would affect all beds down to basement or some underlying truly impermeable layer. Slow drainage continues from each interbed as long as excess pore pressures exist in that interbed. Injection of wastes into clay or shale interbeds would cause a sharp increase in pore pressures in these interbeds. Subsidence areas are usually poor candidates for waste-disposal sites. Generally, they have demonstrated their close communication with the groundwater system, their direct response to pressure changes, and their high compressibility. Heavily depleted artesian aquifers are not empty reservoirs ready for refilling. Rather, the groundwater systems are full and adjusting to the various stresses imposed on the basin. Compaction recorders show that pore pressures throughout the vertical section respond rapidly to pumping stresses. Horizontal and vertical ground movement, caused by horizontal and vertical groundwater flow, can be a serious threat to surface or buried structures. Subsidence affects probably 7,000 sq mi in California alone in amounts to 28 ft in a few places, and has caused the failure of thousands of deep and shallow water and oil wells. Horizontal shear stresses and surface tension cracks are a continued threat in a developing groundwater basin. Saline-water bodies in a basin are not necessarily permanently out of touch with the circulation system of the basin. Hydrologic stresses may force some of this saline water into the circulating groundwater system. Evidence suggests that upward seepage stresses may extend below the freshwater-saline water interface; also, in some areas, saline water may be moving upward into the freshwater zones. Few regions of a groundwater basin are isolated from the circulating flow system. Although injecting liquid wastes deep underground is sometimes expedient, the effects are complex and never ending. Long-lived radioactive wastes require isolation from the hydrosphere for periods of time ranging from 1,000 to several hundreds of thousands of years, but much waste material, to be safe, must be contained forever. And who can anticipate future natural and manmade stresses on the system? End_of_Article - Last_Page 1600------------

Drilling in 1,300 Feet of WaterSanta Barbara Channel, California

Available technology and equipment have proven adequate for carrying out successful floating drilling operations in water depths to 1,300 feet on federal leases in the Santa Barbara Channel of California. System elements directly affected by water depth have performed satisfactorily with only a few minor design modifications. Introduction During the 12-month period following the Feb. 6, 1968, federal lease sale in the Santa Barbara Channel, Humble drilled 10 wells with floating rigs, three of which are in water depths of 900 to 1,300 ft. The adequacy of advance planning has been demonstrated by the fact that few problems have occurred directly related to water depth. The first of the deep-water wells was spudded in 994 ft of water on Aug. 5, 1968 (Fig. 1). This rig (WODECO IV) bas now completed the drilling of a well in 1,300 ft of water. The first deep-water well for the second rig (Blue Water II) was spudded in 941 ft of water on Dec. 3, 1968. (See Fig. 2)It is our purpose here to present information on the location and environment of the deep-water drilling program; the criteria governing selection of the jigs used; details of the systems used, including design considerations and methods; and operating procedures and results. The Santa Barbara Channel Winds, Waves and Currents The Santa Barbara Channel is an area of the Pacific Ocean that is bounded on the north by the portion of the California coastline extending from Point Conception on the west to Ventura on the east and is bounded on the south by the Channel Islands of San Miguel, Santa Cruz and Anacapa. Industry's previous experience with floating drilling in the Channel had shown the environment to be relatively mild. Oceanographic and meteorological references provided the best available data on winds, waves and currents for guidance in selecting and designing equipment and in formulating operating practices. (Fig. 1 shows sites in the area covered by specific reports.) Historical data indicated that the probable yearly maximum conditions in the central Santa Barbara Channel would not exceed 5-minute average winds of 65 knots from the west and northwest or from the east and southeast; significant wave heights of 16 ft with a period of 13 seconds (Maximum waves associated with this sea state would probably be approximately 30 feet.); surface or near-surface currents of 2.4 knots parallel to the California coastline. The data showed parallel to the California coastline. The data showed generally that these conditions would occur for only a very small percentage of the time in winter months in the main part of the Channel east of Point Conception. Near the west end of the Channel, a yearly maximum significant wave height of 18 feet might occur with somewhat greater frequency. Criteria for Rig Selection On the basis of the water depths for the leases offered, the rig selection criteria emphasized deep water operations and the economics of timing. Factors considered for selecting from the available vessels are as follows. Sufficient drilling-depth capability of the rig. Strength and stability of basic hull configuration. JPT P. 27

Abandonment and Salvage of Deep Water Wells and Structures

Abstract This paper presents the method used to restore production following extensive damage to production platforms in West Delta Block 117 caused by Hurricane Betsy. Following the storm, it was necessary to kill several wells and survey the damage to determine how to proceed in salvage operations. Killing wells with wellheads completely missing and all ceasing sheared off under water required the development of new tools to bring the wells under control. The survey showed the platforms could not economically be rebuilt. The wells were plugged and abandoned; production will be restored by redrilling from a new platform. Platforms and conductors were cut off below the mud line and salvaged. Salvage operations created many problems since all work had to be done at water depths of 30 to 214 ft with most work below the 100-ft depth level. A prolonged submergence system of diving was first used in the Gulf of Mexico during this operation. Jet cutters were developed for installation by divers to cut tubular members from the outside. The over-all operation resulted in the use and development of new ideas and tools that may have future application in the oil industry. Introduction Damage to the offshore petroleum industry resulting from Hurricane Betsy, Sept. 9, 1965, was of major proportions. The eye of the hurricane (Fig. 1) crossed the Louisiana coast in the heart of the oil industry. It came from the southeast through the South Pass, Main Pass, West Delta and Grand Isle blocks and went ashore near Grand Isle with a 9-ft tidal wave. Offshore platforms suffering major damage were located within 8 miles of the center of the eye of the storm. Gulf Oil Co.'s two platforms in West Delta 117 were within the eye and were subjected to the maximum forces of the hurricane. These two platforms sitting in approximately 210 ft of water were designed on criteria approximating a 100-year storm force and were subjected to winds of 150 mph and waves of 40 ft or more. It is not known whether wind, waves, debris or all three were responsible for the destruction of the platforms. Debris from hurricanes is increasing yearly and becomes more of a factor in possible damage to offshore facilities with each passing year. A hurricane capable of producing waves comparable to Betsy will, according to one oceanographer, affect an average 50 nautical mile-wide segment of the Louisiana coastline once every 257 years. However, the recurrence interval of a storm of the intensity of Betsy in the Gulf Coast is every 20.6 years. Fig. 2 depicts a platform. typical of the type installed in West Delta Block 117. On Sept. 11, 1965, an aerial survey of the area showed Gulf's most severe damage (offshore) to be in Block 117. The unpleasant sights to greet the eyes of the observers were the flowing wells at the site of the A Platform and nothing where B Platform should have been. Initial Survey of Production Platforms A group of divers and their associated equipment were loaded onto a cargo boat and dispatched to West Delta Block 117 to determine the condition of Platforms A and B. After spotting the cargo vessel near Platform A, an attempt to survey the platform was unsuccessful due to high winds and seas and an inadequate anchoring system on the boat. A derrick barge was then sent to Platform A, and the divers transferred to the barge. JPT P. 267ˆ

Hydraulic Gravel Packing for Deep Water Wells

AbstractThe practice of placing gravel by the hydraulic method of pumping gravel into the well bore or underreamed section of the hole and into the annular space around the screen sections and blank liner is discussed.

Opportunities for Petroleum Development in Arizona: ABSTRACT

Arizona may be divided into two principal parts on the basis of geological features. Most of the northern half, except in the extreme west, belongs to the Plateau province and is characterized by dominantly horizontal strata deformed by uplifts, downwarps, and high-angle faults. The remainder of the state belongs to the Basin-and-Range province, and is composed of linear ranges, mostly oriented with northwest-southeast trends, and separated by wide, deep valleys filled largely with Tertiary and later alluvium. Overthrusts and many compressional features are represented in the mountain structures. To date no significant petroleum discoveries have been made in Arizona. The Basin-and-Range portion, furthermore, offers encouragement for prospecting in few places. Its valleys, except possibly in the extreme southwestern part of the region, appear to be filled with continental sediments; deep water wells have exposed nothing to justify optimism. In contrast, certain features of the Plateau province favor more exploration in that area. Rocks similar in type and age to those forming parts of the plateau of northern Arizona have produced petroleum in adjoining areas of southern Utah and northwestern New Mexico. Studies of End_Page 2379------------------------------ the distribution and thickness of these strata and of possible basins of accumulation within them, are discussed. Recent developments in exploration of this area are briefly summarized. End_of_Article - Last_Page 2380------------