Pressure drawdown and buildup tests information derived from tests. Pressuredrawdown test analysis of a gas wellapplication of new. Various diagnostic plots were performed to determine each wells flow capacity normalized by lateral length. Pressure drop in a production well inside a finite reservoir. Reservoir conditions, such as the tendency to produce sand, may limit the drawdown that may be safely applied during production before damage or unwanted sand production occurs. The pumping rate is then increased to a higher constant rate and the well is pumped until the drawdown stabilises once more figure 5.
Introduction a pressure drawdown test is simply a series of bottomhole pressure measurements made during a period of flow at constant production rate. Therefore, there is no need to bump the choke to maintain a constant rate. The well test data of all cases were generated from reservoir simulation. Pressure drawdown testing techniques for oil wells. Drawdown is the drop in the level of water in a well when water is being pumped. Tests on oil and gas wells are performed at various stages of drilling, completion, and production. Pressure build up and draw down test analysis duration. A pressure drawdown test was carried out in an undersaturated oil reservoir. The well pressure response can be modeled as a function of its interconnectivity with the fracture network. The drawdown, and therefore the production rate, of a producing interval is typically controlled by surface chokes. Surface chokes are helpful in controlling the pressure drawdown. The measurement and analysis of pressure data taken after a well is put on production, either initially or following an extended shutin period.
A drawdown test is one in which the rate is held approximately constant while the well pressure is measured. The interpreted pressure transient test is a primary source of dynamic reservoir data. Permeability to the produced phase oil, gas, or water, which is an average value within the radius of investigation achieved in the test. In addition, the buildup test is conducted to obtain initial reservoir pressure during. Usually the well is closed prior to the flow test for a period of time sufficient to allow the pressure to stabilize throughout the formation, i. The step drawdown test in mw112 was conducted on may 10, 2006. The best practice for a drawdown is to do a constantchoke test, not necessarily a constant rate test. An average pumping rate of less than 1 gallon per minute gpm was determined to be the optimum pumping rate baed s on the july 4, 2012ste p drawdown pumping test at tew112. Pdf pressure and temperature drawdown well testing. The objectives of a drawdown test are to determine skin, perm and the distances to the reservoirs boundaries. In subsurface hydrogeology, drawdown is the reduction in hydraulic head observed at a well in an aquifer, typically due to pumping a well as part of an aquifer test or well test.
Ideally, the well should be producing at constant rate but in practice, this is difficult to achieve and drawdown pressure data is erratic. Bop pressure testing procedure 1 discuss operator bop requirements with rig manager. This is especially true for new wells, in which well cleanup commonly occurs for days after. Pressure buildup and drawdown tests provide an opportunity to obtain estimates of the following well and reservoir properties. Virginia department of health well yield and drawdown pump test procedures these procedures are designed specifically for wells located outside of one of the coastal plain groundwater management areas and when a deq aquifer test is not required. Since you cant see a boundary until the pressure wave hits it. Make sure all rams and annular are open and if applicable hcr is closed.
Drawdown data are usually noisy, meaning that the pressure moves up and down as fluid flows past the gauges and minute variations in flow rate take place. Pressure drawdown definition and meaning collins english. The drawdown test is a fundamental laboratory technique which is used to evaluate interactions between flat surfaces such as film, foil, and paper and a myriad of inks, coatings, paints, suspensions, adhesives, colloids, powders, etc. Insure that all romfors bop equipment is tested consistent with romfors policy. On the following pages, you will learn the basic vocabulary of drawdown, ways to make drawdown measurements and tips for recording and using your findings. Jan 23, 2020 the precharges may range from 5003,000 psi, with the desired precharged pressure dependent on the service conditions during fluid drawdown. A new method of drawdown pressure test analysis is proposed that takes into consideration the nondarcian flow as well as the skin and boreholestorage effects. Pdf pressure transient tests of gas wells, in general, are peculiar in their nature.
In waterrelated science and engineering, there are two similar but distinct definitions in use for the word drawdown. For an infiniteacting multiplewells system, pressure drawdown equation is already obtained by using superposition principle. When sand is produced from a reservoir the surface chokes also limit the pressure drawdown. Basic concepts in well testing for reservoir description. With no need to lose production, reservoir size can be determined. They possess additional degree of difficulty when compared.
Pressure drawdown is the difference between the reservoir pressure and the flowing. Pressure drawdown is the differential pressure which helps in moving hydrocarbons from a reservoir into the wellbore. Classical well test interpretation depends on simplified analytical models and graphical techniques. A new method of drawdownpressure test analysis is proposed that takes into consideration the nondarcian flow as well as the skin and. Fig, 1671 is a drawdown curve for three different precharge pressures and is used to size preventers with respect to accumulator pressure. Jan 28, 2003 applications to the simulation of pressure drawdown well tests are presented, for complex situations where the well intercepts a random fracture network with various fracture densities and conductivities. A drawdown is the peaktotrough decline during a specific recorded period of an investment, fund or commodity. Pressuredrawdown test analysis of a gas wellapplication of. We recommend doing a drawdown test to look for reservoir limits instead of running a buildup because a flowing well test does not interrupt cash flow. Two new correlations obtained from numerically simulated drawdown tests are used and the method of application is illustrated. Since you cant see a boundary until the pressure wave hits it, theres no way to tell how long a buildup is required to see the reservoir limits.
This paper presents pressure drawdown equations of a multiplewells system in a circular cylindrical reservoir with constant pressure outer boundary. Canal lining drawdown tests and development of new drawdown. A pressure drawdown test is simply a series of bottomhole pressure measurements made during a period of flow at constant production rate. Mw112 is a 6inch diameter groundwater monitoring well, installed to a total depth of approximately 48 feet below grade with a screened interval from 15 to 48 feet below grade.
A comprehensive system of wizards is designed to guide the user through the appropriate steps to ensure data is entered properly and that a reliable analysis is obtained. Quite often a well will decline in both rate and pressure on a fixed choke setting. The analysis of flowing periods drawdown is frequently difficult and inaccurate. Pressure drawdown testing techniques for oil wells 4.
Before opening, the initial pressure pi is constant and uniform in the reservoir. Accumulator function test bureau of land management. As shown in table 1, the wells with managed pressure drawdown 1525 psid tubing and casing pressure drop have significantly higher flow capacity and eurs compared with the wells with unmanaged pressure drawdown. This may require nabors to incur the cost for the testing subcontractor as well as provide rig time to the operator for the test. The pressure response pressure signature is measured and matched to a mathematical model equation or graph. Pressure drawdown well tests in fractured porous media i. A pressure test is conducted by giving the well at least one perturbation in flow rate. Pressure transient analysis using generated well test data from. The new drawdown criteria developed for the canal call for a steady series of canal drawdown steps whose maximum size varies depending on the time interval between steps. Accumulator drawdown test drilling engineering netwas. Shutin the well decreasing the bottom hole pressure interference test pulse test producing well measure pressure in another shutin well away from the producer communication test gas well test back pressure, isochronal test, modified isochronal test well productivity, aofp, non darcian skin. Drawdown test is ideally performed when the pressure is equalized throughout the. Introduction the measurement and analysis of pressure data taken after a well is put on production, either initially or following an extended shutin period.