1. Field of the Invention
This invention relates to the hydraulic fracturing of oil and gas wells. In particular, skid-mounted equipment to form a “Mobile Frac Plant” is provided, along with an improved method for marketing and executing hydraulic fracturing operations.
2. Description of Related Art
Hydraulic fracturing of wells became commercial in the U.S. in 1949, using a single truck and small volumes of hydraulic fracturing fluid. The process has been continuously improved, with increasing amounts of fluid and increasing horsepower to pump the fluids into a well. A new era in hydraulic fracturing began in recent years, when it was found that wells can be drilled horizontally for large distances through shale zones and hydraulically fractured at multiple locations along the horizontal section of the well. This new capability for producing “shale gas” has opened vast natural gas resources to economic development, changing the world energy outlook to an extent unimagined a few years ago. A recent survey of shale gas fracturing is provided in the paper SPE 133456, “Thirty Years of Gas Shale Fracturing: What Have We Learned?,” Society of Petroleum :Engineers, 2010. Still, hydraulic fracturing in vertical wells continues to make possible recovery of hydrocarbons from wells that could not be economically drilled without a following fracturing treatment. Over 70 per cent of wells drilled today in the U.S. are hydraulically fractured soon after drilling.
In recent years, fracturing of shale from horizontal wells to produce gas has become a major part of the hydraulic fracturing market. To perform a fracturing treatment of a horizontal well, it is common for 15,000 to 30,000 hydraulic horsepower, supplied by pumps mounted on a fleet of trucks, to be moved to the well site. The quantities of fluid and proppant to be pumped and the flow properties of the fluid needed for a particular well are determined by the frac design.
In vertical wells, apparatus for hydraulic fracturing is commonly used for one day at a well then moved to another well. When hydraulically fracturing horizontal wells, multiple stages of fracturing occur in a single well. There are reports of as many as 30 to 40 fracturing treatments in a single horizontal well. There may be multiple wells per location. Therefore, hydraulic fracturing equipment at the surface may remain at the same location for a number of days or weeks.
The combination of various equipment used for hydraulic fracturing of a well is known in the industry as a “spread,” The “frac spread” includes truck-mounted pumps, a blender used for mixing chemicals and proppant into the fracturing fluid, a manifold and flow lines connecting the pumps to a well head. The industry business model for a pumping service company has been to fracture one or a few stages in a well and demobilize the trucks and equipment for a move to another well. Mobile equipment for short-term utilization that can be quickly demobilized was of paramount importance. Fleets of thousands of pump trucks with these capabilities have been created, each having a tractor and trailer or a truck-mounted pump for connection to a mixing system. The present pumping service industry is, to a large degree, made up of trucking companies that also pump water and sand. But the operations of a pumping service company change dramatically when fracturing horizontal wells. Typically, twelve to twenty trucks move onto a well site at one time and stay for days, often weeks. When the job is completed, this fleet of trucks typically moves directly to another well site and also stays there for weeks, rarely going to their home yard. Each truck requires at least one DOT driver, who normally stays with his truck, idling the engine continuously for days, occasionally increasing RPMs when a frac is actively being done in effect, the driver must operate on the highways, moving the equipment on and off location, and operate the complex equipment. Often on a frac job as many as fifty people are required at any given time due to all the tractors and pressure pumping equipment being utilized. There are too many people on location. Most have little to do most of the time but sit in their truck. Trucks notwithstanding, the actual number of people required is less than half. A well site is a dangerous place, and having 25-30 non-essential personnel on location, round the clock poses both safety issues and adds a very high operating expense to the operation. There is a need to have only personnel that are necessary on the well site.
The most dangerous activity the pumping service does today is moving such heavy equipment over the highways. This is done with drivers, while DOT certified, whose primary job is to operate High Pressure/High Temperature (HPHT) pumps and other equipment. Often drivers asked to move equipment after working an “operational shift” are fatigued as they leave the well site. This can present safety issues on the highway. In fact, the most dangerous activity includes driving on public highways. There is a need to establish a system where professional equipment movers move the equipment, and leave the frac'ing to those who know that business best.
There are also too many trucks on location. This requires a large footprint to accommodate so much heavy equipment and a large amount of fuel to keep the many trucks idling for weeks. The trucks cause continuous noise pollution and diesel exhaust emissions. The noise and smell of exhaust may be apparent for up to a mile, or even further, from such locations. Also, pumping service companies have too much capital tied up in tractors for frac spreads intended for high mobility that move only every week or two.
Oil and gas producers operate on small margins when drilling “unconventional plays' in North America. Pumping service companies providing hydraulic fracturing have a need to work on a highly efficient business model to enable the robust drilling programs that are necessary in today's industry. A new, more nearly optimized hydraulic fracturing paradigm is necessary. The industry has an over-abundance of one to five stages per day frac capacity. The market needs a “fit-for purpose” apparatus and method that is optimized for shale gas development programs in North America and around the world.
There is a need for an improved and optimized fracing system that can bring a spread to a well site having the same pumping capability as prior art spreads but that reduces capital and operational costs, decreases the number of people on location, over-the-road risks, footprint of the spread, air pollution, noise, and energy consumption and increases well site safety.
A variety of patents describe equipment innovations for decreasing costs of fracturing treatments. U.S. Pat. No. 7,051,818 discloses a combined power unit for a nitrogen injection system by coil tubing. A prime mover engine coupled to coil tubing and fluid units is mounted on a single trailer or skid, which can be dropped off at a jobsite—a tractor is not required to remain with the trailer Or skid, U.S. Pat. No. 4,724,907 discloses equipment for mixing surfactants and water and an oil solvent for injection into a well. The equipment may be mounted on a skid. U.S. Pat. App. Pub. No. 2009/0301725 discloses apparatus to prevent flow of proppant through the high-pressure pumps, so as to decrease wear of the pumps.
The procedures used for marketing and organizing hydraulic fracturing services in the industry have not changed significantly for many years.
Service companies compete to sell services and products to well operators based. primarily on price and service. Price books are published by pumping service companies, listing pumping costs, chemicals, proppants, transportation and other costs separately, but deep “discounts” are made from the price books for the total treatment cost. An operator may set an objective for a well treatment and obtain bids from two or more service companies for a total price of a treatment. Because price books are not followed, there is very limited transparency to the cost of each component of the treatment, so that the operator cannot arrive at the optimum. treatment for his circumstances. Also, an operator may benefit by purchasing components of the fracturing treatment—such as proppant, polymer and chemicals—from third-party suppliers. But, this decision is not possible when the cost of each component that is actually being charged an operator is not known to the operator or customer. There is a need for a method for marketing and executing fracturing treatments that makes the process of purchasing a treatment transparent to a customer and allows the customer to select an optimum treatment for his well based on computer-readable data and interactive cost calculations.
A Mobile Fracturing Plant is provided. Equipment is mounted on skids and is delivered to a well site and unloaded. Pumps may be powered conventionally or by electrical power produced at the well site by natural gas. A method of using the mobile equipment is provided. A method for preparing a bid or cost estimate for treating a well by hydraulic fracturing is provided, using price information and calculations of total cost in a computer system. Price of each item making up the cost of a treatment is provided to a customer in terms of cost per unit of consumption and the customer can use a computer system to obtain the total cost of a treatment. Third-party purchases may be included in the calculations.
Persons normally present at a well site and their locations are indicated by symbols, such as symbol 11. It is not uncommon for about 50 persons employed by the pumping service company to be present at the well site. These persons are indicated by the symbols at different locations and associated with different equipment in the frac spread. Including support crews, there may be as many as 70 people around the well.
The blended fluids under high pressure (often as high as 10-45,000 psig) and proppant are pumped into the well, fracturing the surrounding formation. The proppant “props” and holds the fractured formation open to enhance rate of gas or oil recovery. The fluid is normally water. A polymer such as polyacrylamide is usually added to the water to decrease friction loss as the water is pumped down a well. (Water containing the polymer is usually called “slick water,”) Other polymers may be used during a treatment to form a more viscous fluid. Proppant is added to the fluid to prevent closure of fractures after pumping stops. Other chemicals, such as biocides, corrosion inhibitors, clay stabilizers and other chemicals may be added in small concentrations. Proppants, polymers and other chemicals are supplied by well-known suppliers in industry. In conventional treatments, these materials are purchased by the service company.
The present invention (see
The Mobile Frac Plant is tailored to be moved onto location quickly by flatbed trucks, is mobilized and demobilized quickly, eliminates unnecessary personnel on location, and totally eliminates diesel tractors sitting at idle for weeks at a time. This results in a reduction of both capital expense costs for equipment purchase and operational costs in personnel and fuel. Other advantages are reduced noise, reduced carbon dioxide and carbon monoxide emissions, and a marked reduction of the footprint requirement on the fracturing pad. Also, personnel safety is greatly enhanced as fewer people are exposed to the dangerous environment of the well site. Professional moving companies may be employed to mobilize and demobilize the Mobile Frac Plant, thereby effectively managing the risk of moving the equipment over the highways.
a) illustrates skid-mounted pumps for use in the Mobile Frac Plant of
Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims. It is understood that modifications to the invention may be made as might occur to one skilled in the field of the invention within the scope of the appended claims. All embodiments contemplated hereunder that achieve the objects of the invention have not been shown in complete detail. Other embodiments may be developed without departing from the spirit of the invention or from the scope of the appended claims. Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.
This application claims priority to provisional application Ser. No. 61/392,376 filed on Oct. 12, 2010
Number | Date | Country | |
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61392376 | Oct 2010 | US |