CHAPTER 14 GROUND WATER CONTAMINATION, EXTRACTION, AND INJECTION ISSUES AFFECTING THE OIL AND GAS INDUSTRY

JurisdictionUnited States
Ground Water Contamination
(May 1991)

CHAPTER 14
GROUND WATER CONTAMINATION, EXTRACTION, AND INJECTION ISSUES AFFECTING THE OIL AND GAS INDUSTRY

Dianne R. Nielson, Ph.D.
Division of Oil, Gas and Mining State of Utah
Salt Lake City, Utah


INTRODUCTION

The earliest legal issues affecting the development of oil and gas concerned ownership not environmental protection. Early regulation and case law speak to issues of conservation, waste, capture, correlative rights, property rights, and lease rights. While individual states independently established bodies of regulation governing drilling and production, the first coordinated effort to establish consistent conservation statutes and regulations came with the formation of the Interstate Oil Compact Commission (IOCC) in 1935. Much of the law governing segregation and protection of aquifers was established with the support of the IOCC. The extensive environmental and planning regulations governing oil and gas development are part of the much broader body of federal laws enacted during the 1970s.

As with ground water regulation in general, ground water protection during oil and gas exploration and production is governed by the Clean Water Act,1 the Safe Drinking Water Act,2 the Resource Conservation and Recovery Act,3 (RCRA) and equivalent statutes and regulations in states with primacy for program regulation. Exploration and production of oil and gas are governed by the state's conservation statute4 and on federal lands, under the Mineral Leasing Act of 19205 , the Federal Land Policy and Management Act6 and Federal Onshore Orders and Notices To Lessee,

[Page 14-2]

as well as the National Environmental Policy Act7 and federal land use planning acts.8

Potential ground water contamination associated with oil and gas operations may result from either or both of the following sources: 1) naturally occurring materials which are produced in conjunction with oil and gas extraction, such as produced water, and 2) wastes or residues generated directly as a result of oil and gas operations, such as drilling mud, fluids used to stimulate production, and residues from tank bottoms. In the first case, the fluids are only a problem if they contaminate drinking water sources or surface environments. If they are reinjected into and confined within unusable, subsurface horizons similar to their origin, there is no contamination. In the second case, there is no natural environment for the wastes. The method of disposal is dependent on the toxicity, or lack of toxicity, of the waste.

The objectives of this presentation are to 1) identify potential for ground water contamination resulting from extraction and injection activities associated with oil and gas exploration and production operations, and 2) discuss impact of proposed regulatory changes regarding ground water protection as these changes relate to oil and gas operations. Issues of particular concern or current focus include: disposal of produced water, improperly plugged and abandoned wells, and reauthorization of RCRA as it relates to exploration and production waste. Consideration will also be given to effective coordination of environmental and conservation concerns under multiple agency regulatory authorities.

While it is possible to address these objectives for the full gamete of exploration, production, transportation, refinery, and storage/distribution aspects of the petroleum industry, this presentation will focus on impacts specifically related to oil and gas exploration, production, and reclamation.

OIL AND GAS EXPLORATION AND PRODUCTION

Drilling and Completion of a Production Well

State and federal laws require approval of an Application for Permission to Drill (APD) prior to commencing drilling. The approval prescribes how the well will be drilled, completed for

[Page 14-3]

production, and plugged and abandoned upon completion of exploration or production. The purpose is to conserve the oil and gas resource, protect other subsurface resources, of particular note in this case fresh water aquifers, and protect the surface environment. Drilling and production of oil and gas create surface and subsurface disturbance, both of which can be mitigated during ongoing operations and reclaimed when exploration or production is completed.

In order to understand the potential for ground water contamination, it is helpful to understand how the well is drilled and produced.

Surface Facilities

The type of surface facilities and disturbance associated with drilling and production are dependent on the type of production.9 The proposed well site is inspected and the location of facilities is agreed to by the operator and the regulatory agency(ies) prior to approval of the APD. The purpose of this is to ensure that the surface environment, including human and wildlife concerns, is protected during drilling and production operations, and that the site can be reclaimed following exploration or production.

Under these procedures, protection of the environment is factored into the planning and construction of the site. Non-standard construction costs also are factors in the economics of the well, affecting the cost of drilling. Furthermore, the ability to relocate the drillsite is not simply a factor of additional cost. Depending on the nature of the geologic target, ability to relocate a proposed site may be severely limited.

During drilling the wellbore penetrates a variety of different rock types or formations. Particular rock layers or zones may contain and transmit fluids (porosity and permeability) more effectively than others, and hence some zones may contain significant amounts of fresh water, while other zones may serve to trap crude oil, natural gas, and associated brackish or saline water.

When initially drilled, the wellbore provides communication between all intervening rock formations and associated

[Page 14-4]

fluids. In order to prevent caving or collapse of the upper portion of the wellbore, surface casing is cemented to the surface. As additional smaller diameter casing is inserted after deeper drilling, it is cemented sufficiently to protect all strata and prevent communication between formations. If economically producible quantities of oil or gas are not encountered, the wellbore is cemented to prevent migration of fluids. The surface location is reclaimed and restored to original contour and revegetated. If oil or gas can be economically produced, the well will be completed for production. In order to control extraction of oil and/or gas, and prevent contamination or communication of fluids from the various rock horizons, casing is inserted in the wellbore and cemented as necessary. The purpose of the cement is to fill the space between the wellbore and the casing, preventing migration of fluids in the space between the wall of the wellbore and the casing, and holding the casing in place. The well will then be completed for production from one or more zones, generally by creating holes or perforations through the casing and the cement so that oil and gas can migrate from the production zone into the cased wellbore, where it flows or is pumped to the surface. During the initial completion of the well, a variety of procedures, including hydraulic fracturing or acidizing of the production zone, may be performed to enhance production. These procedures are designed to enhance the fracture space or permeability of the rock in the production zone directly adjacent to the wellbore, hence increasing migration of oil or gas into the wellbore.

Upon completion of the production phase, the cased wellbore is cemented or otherwise plugged to prevent migration of fluids and the surface location is reclaimed.

State and federal regulatory requirements include filing by the operator of electric logs, which can be used to interpret rock types and potential production zones; cement bond logs, which delineate the continuity of the cement between the rock formation and the casing; and reports of fresh water encountered during drilling. Monthly production and disposition of production, including crude oil, natural gas, and produced water are required for producing wells. Reporting requirements were originally established to provide a check on production volumes. They also enable tracking of revenues, royalties, and taxes from...

To continue reading

Request your trial

VLEX uses login cookies to provide you with a better browsing experience. If you click on 'Accept' or continue browsing this site we consider that you accept our cookie policy. ACCEPT