Abstract: A method for providing a well injection program in which an evaluation of plugging of the sandface over time is included to more accurately determine the water treatment facility specifications and well injection parameters for a produced water re-injection well. An artificial produced water is provided which includes both water wet solids and oil wet solids being representative of the treated produced water to be injected, at solids and oil content concentrations magnitudes of order greater than the treated produced water. This allows filtration testing on small injected volumes suitable for standard laboratory equipment. The areal spurt loss and Carter's Leak-Off coefficient are then determinable for use in evaluating the plugging of the sandface over time.

Abstract: A method of condition monitoring of tubing (10) in an injection well (12). A baseline measurement of friction loss in the tubing is taken by obtaining pressure responses at the wellhead (34) and downhole for a number of injection rates. After a period of time, pressure responses at the wellhead and downhole are taken when the well is shut-in. Analysis of the Instantaneous Shut-In Pressure (ISIP) at the wellhead and downhole on shut-in provide the friction loss in the tubing for the last injection rate before shut-in. A comparison can be made with the baseline measurement of friction loss to indicate deterioration of the inner surface of the tubing if the friction loss has increased. The baseline measurement may be made using a step rate test or by analysis of the combined ISIP.

Abstract: A method of condition monitoring of tubing (10) in an injection well (12). A baseline measurement of friction loss in the tubing is taken by obtaining pressure responses at the wellhead (34) and downhole for a number of injection rates. After a period of time, pressure responses at the wellhead and downhole are taken when the well is shut-in. Analysis of the Instantaneous Shut-In Pressure (ISIP) at the wellhead and downhole on shut-in provide the friction loss in the tubing for the last injection rate before shut-in. A comparison can be made with the baseline measurement of friction loss to indicate deterioration of the inner surface of the tubing if the friction loss has increased. The baseline measurement may be made using a step rate test or by analysis of the combined ISIP.

Abstract: A method for providing a well injection program in which injection testing is performed on an existing well which is intended to be an injection well in a field development. Water is injected into the well in a series of step rate tests or injection cycles, the data is modelled to determine thermal stress characteristics of the well and by reservoir modelling the optimum injection parameters are determined for the well injection program to provide for maximum recovery. The thermal stress characteristics are those that would previously have been obtained from core samples when the well was drilled. Further wells on a development can be tested and the individual thermal stress characteristics of each well combined in the reservoir model for optimized field development.

Abstract: A method for determining cross-flow in an injection well in a multi-layered reservoir. Wellhead pressure measurements are made and the characteristic curve analysed to identify late wellbore storage indicating cross-flow. The water hammer pressure wave can also be analysed at shut-in to identify the presence of sand fill in the rat-hole. By measuring the wellhead pressure, intervention-less and continuous monitoring of the injection well is available so action can be taken to reduce sand production and maintain injectivity.

Abstract: A geothermal power plant and method of operating a geothermal power plant in which control over the creation and growth of fractures in the geothermal formation is achieved. A downhole pressure gauge (14) with a high data acquisition rate is located in the injection or production well. Pressure changes in the well are recorded as a pressure trace and transmitted to the surface as data. The data is analysed to determine fracture parameters of the geothermal formation. The pump rate of the well is then varied in response to the calculated fracture parameter(s).

Abstract: A method for providing a well injection program in which an evaluation of plugging of the sandface over time is included to more accurately determine the water treatment facility specifications and well injection parameters for a produced water re-injection well. An artificial produced water is provided which includes both water wet solids and oil wet solids being representative of the treated produced water to be injected, at solids and oil content concentrations magnitudes of order greater than the treated produced water. This allows filtration testing on small injected volumes suitable for standard laboratory equipment. The areal spurt loss and Carter's Leak-Off coefficient are then determinable for use in evaluating the plugging of the sandface over time.

Abstract: A method for providing a well injection program in which injection testing is performed on an existing well which is intended to be an injection well in a field development. Water is injected into the well in a series of step rate tests or injection cycles, the data is modelled to determine thermal stress characteristics of the well and by reservoir modelling the optimum injection parameters are determined for the well injection program to provide for maximum recovery. The thermal stress characteristics are those that would previously have been obtained from core samples when the well was drilled. Further wells on a development can be tested and the individual thermal stress characteristics of each well combined in the reservoir model for optimized field development.

Abstract: A dynamic monitoring system for dynamically monitoring injection operations on wells by determining the extent of fracturing using downhole pressure measurements. The system comprises a downhole pressure gauge, means to transmit data from the downhole pressure gauge to the surface and a surface data acquisition unit wherein, on inducing a pressure change in a wellbore by an injection operation, the downhole pressure gauge records a pressure trace as data, the data is transmitted to the surface at a first sampling frequency, the data is stored in the surface data acquisition unit and fracture length is calculated from the stored data to indicate extent of fracturing. Sampling frequencies are outside the known operating ranges.

Abstract: A method for providing a well injection program in which injection testing is performed on an appraisal well. An appraisal well is selected, downhole sensors are located in the well to measure pressure and temperature, water is injected into the well in a series of step rate tests or injection cycles, the data is modelled to determine a thermal stress characteristic of the well and by reservoir modelling the optimum injection parameters are determined for the well injection program to provide for maximum recovery. This overcomes the need for making thermal stress characteristic measurements on core samples.

Abstract: A method of determining the presence of hydrocarbon-filled natural fractures with sufficient lateral extension in a well in which stimulation by hydraulic fracturing is intended to be carried out. Following perforation of an interval, a fluid is pumped into the well and a pressure response trace is collected. The fluid is pumped at a rate which is lower than the pump rate for the intended frac job and the data collection rate is higher than the data collection rate for the intended frac job. Characteristic elements are identified in the pressure response trace whose value and combination indicate the presence or absence of hydrocarbon-filled natural fractures with sufficient lateral extension in the interval.

Abstract: A method of increasing hydrocarbon production by hydraulic fracturing in shale formations by using an a-seismic process of cyclic injection of cooled aqueous fluid at a low rate with shut-in periods to induce tensile failure in the formation and create a fracture network of high and very high conductivity fractures with sufficient lateral extension in a completed well. A final single cycle of aqueous fluid and proppant is used in which the volume of proppant has been determined from measurements of the downhole pressure. Further fracture parameters being: volume of the very high conductivity fractures, lateral extension of the very high conductivity fractures, surface of the very high conductivity fractures and estimation of the global fracture network shape are determined and analysed after each injection cycle.

Abstract: A geothermal power plant and method of operating a geothermal power plant in which control over the creation and growth of fractures in the geothermal formation is achieved. A downhole pressure gauge (14) with a high data acquisition rate is located in the injection or production well. Pressure changes in the well are recorded as a pressure trace and transmitted to the surface as data. The data is analysed to determine fracture parameters of the geothermal formation. The pump rate of the well is then varied in response to the calculated fracture parameter(s).

Abstract: A method of determining the presence of hydrocarbon-filled natural fractures with sufficient lateral extension in a well in which stimulation by hydraulic fracturing is intended to be carried out. Following perforation of an interval, a fluid is pumped into the well and a pressure response trace is collected. The fluid is pumped at a rate which is lower than the pump rate for the intended frac job and the data collection rate is higher than the data collection rate for the intended frac job. Characteristic elements are identified in the pressure response trace whose value and combination indicate the presence or absence of hydrocarbon-filled natural fractures with sufficient lateral extension in the interval.

Abstract: A method of increasing hydrocarbon production by hydraulic fracturing in shale formations by using an a-seismic process of cyclic injection of cooled aqueous fluid at a low rate with shut-in periods to induce tensile failure in the formation and create a fracture network of high and very high conductivity fractures with sufficient lateral extension in a completed well. A final single cycle of aqueous fluid and proppant is used in which the volume of proppant has been determined from measurements of the downhole pressure. Further fracture parameters being: volume of the very high conductivity fractures, lateral extension of the very high conductivity fractures, surface of the very high conductivity fractures and estimation of the global fracture network shape are determined and analysed after each injection cycle.

Abstract: A dynamic monitoring system for dynamically monitoring injection operations on wells by determining the extent of fracturing using downhole pressure measurements. The system comprises a downhole pressure gauge, means to transmit data from the downhole pressure gauge to surface and a surface data acquisition unit wherein, on inducing a pressure change in a wellbore by an injection operation, the downhole pressure gauge records a pressure trace as data, the data is transmitted to surface at a first sampling frequency, the data is stored in the surface data acquisition unit and fracture length is calculated from the stored data to indicate extent of fracturing. Sampling frequencies are outside the known operating ranges.