Abstract:
A method of diagnosing flow through an inflow control device includes, producing or injecting fluid through an inflow control device, measuring temperatures near or at the inflow control device over time while producing or injecting fluid therethrough, and attributing temporal changes in temperature to changes in the fluid that is produced or injected.

Description:
BACKGROUND 
       [0001]    During the production or injection life of a borehole in an earth formation in the completion industry, for example, it is expected that borehole and formation conditions can change over time and that these changes can alter production or injection. Examples of such changes include increases and decreases in fluid flow rates created by changes in the formation and/or changes in fluid composition (Fluid composition here being defined as relative percentages of gas, oil and water and changes in fluid composition referring to changes in the relative percentages). Different zones along the borehole often change at different times. Changes in one zone can negatively affect production or injection of that zone, of other zones, and of the borehole as a whole. Knowing when changes occur and how such changes affect production or injection through each inflow control device can allow an operator to make changes that could increase overall production or injection of the borehole. Unfortunately, gathering such knowledge can be expensive since it typically includes halting production or injection and running logging tools into the borehole to capture data sufficient to determine what changes in fluid flow rates and fluid composition at different inlet zones has occurred. Methods that permit an operator to gain such knowledge without intervention would be well received in the industry. 
       BRIEF DESCRIPTION 
       [0002]    Disclosed herein is a method of diagnosing flow through an inflow control device. The method includes, producing or injecting fluid through an inflow control device, measuring temperatures near or at the inflow control device over time while producing or injecting fluid therethrough, and attributing temporal changes in temperature to changes in the fluid that is produced or injected. 
         [0003]    Further disclosed herein is a method of determining compositional changes of a fluid flowing through an inflow control device. The method includes, measuring temperatures at selected points relative to the inflow control device at a first time, measuring temperatures at the selected points relative to the inflow control device at a second time, determining differences in temperature at the selected points between the first time and the second time, and attributing temporal temperature differences at the selected points to changes in composition of the fluid flowing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
           [0005]      FIG. 1  depicts a schematic representation of a portion of a downhole completion application wherein methods disclosed herein are deployed; 
           [0006]      FIG. 2  depicts relationships between pressure, temperature and flow rates through various flow devices; 
           [0007]      FIG. 3  depicts a flow chart of a process disclosed herein to calibrate a mathematical model to a simulator; and 
           [0008]      FIG. 4  depicts a flow chart of a process disclosed herein to diagnose a completion operation through comparison to a mathematical model or a simulator. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
         [0010]    Referring to  FIG. 1 , a completion liner  10  as illustrated is positioned within a borehole  14  of an earth formation  18  in a downhole completion operation. The completion liner  10  is sealably engaged to the borehole  14  via a packer  22 . The completion liner  10  includes a basepipe  26  with a distributed temperature sensor (DTS)  30 , or multiple discrete sensors, positioned, inside or outside the basepipe  26 , to monitor temperature therealong in real time either upstream or downstream of a plurality of inflow control devices (ICD)  34 . The plurality of inflow control devices  34 , with three being illustrated in this embodiment, are longitudinally spaced along the basepipe  26  with a node  38  being positioned to either longitudinal side of each of the ICDs  34  thereby designating separation of adjacent zones  42 . Flow rates from various positions along the formation  18  through each of the ICDs  34  can depend upon various factors. For example, permeability of the formation  18  can vary at different positions as well as the ratio of oil to water to gas from each zone  42 . It should be understood, that although examples disclosed herein are directed to production through the drill string  10 , alternate embodiments could just as well be directed to injecting fluids through the completion liner  10 , out through the ICDs  34  and into the formation  18 . 
         [0011]    Although inflow control devices  34  can help to balance production from the various zones  42  along the completion liner  10 , it may be desirable for an operator to alter production through particular zones  42  even further than what is possible through the ICDs  34 . For example, if one of the zones  42  is producing mostly water, it may be desirable to fully close off production from that zone  42 . Additionally, if a zone  42  is producing too fast, partially closing the zone  42  can minimize erosion of the ICD  34  thereby extending the life of the ICD  34  and likely increasing total production from the well in the process. 
         [0012]    Knowing when to make alterations, however, requires knowledge of what is happening at the various zones  42 . Typically this has meant running logging tools within the completion liner  10  to take measurements therealong. Such intervention, however, is costly in terms of labor, equipment and lost production. Consequently, these interventions are used sparingly, possibly resulting in delays that could, if implemented sooner, have had significant benefits to the operation, including increasing production therefrom. Embodiments disclosed herein allow an operator to gain knowledge regarding flow through the ICDs  34 , positioned along the completion liner  10 , without interfering with production therethrough. 
         [0013]    Referring to  FIG. 2 , embodiments disclosed herein build on the fact that specifics of geometry  50  of the ICDs  34  determine flow performance characteristics  46 A,  46 B and  46 C therethrough. For example, the Joule Thompson effect  46 C (change in temperature divided by change in pressure) is a function of the geometry  50  of the ICD  34  and flow rates for any particular fluid having specific fluid properties, such as density and viscosity. Geometry of standard screens  54  and slotted liners  58 , by contrast, do not have pressure drops  62  or cause differential temperatures  66  that could be employed in the techniques disclosed herein. 
         [0014]    Since flow performance characteristics of pressure drop versus flow rate  46 A, temperature differential versus flow rate  46 B and Joule Thompson Effect versus flow rate  46 C are determined by the geometry  50  of the ICD  34  for a specific fluid these flow performance characteristics  46 A,  46 B,  46 C can be both empirically mapped and mathematically calculated. Mapping them may entail measuring actual temperatures at selected points  70 , downstream and upstream of ICDs  34 , and actual pressures at selected locations  74 , along the completion liner  10  while flowing fluids of known ratios of oil to water to gas at known flow rates. The density and viscosity of these fluids, being a function of the oil to water to gas ratio, is also known and is included in the mapping database. By taking such measurements at a variety of different fluids and flow rates the flow performance characteristics  46 A,  46 B,  46 C can be accurately mapped. 
         [0015]    Referring to  FIG. 3 , a process for calibrating the mathematical model to a simulator is shown in flow chart  78 . Schematically, the simulator is configured similar to the completion configuration of  FIG. 1 , the primary difference being that parameters affecting flow through each of the zones  42  of the simulator are controllable and selectable. As discussed, these parameters, among other things, include, fluid ratios of oil to water to gas, fluid viscosity, fluid density and flow rate. The mathematical model includes adjustable variables that when properly calibrated will accurately calculate temperature profiles that strongly correlate with temperature profiles measured. The model is based on mass, momentum and energy equations including Joule Thompson Effect equations. 
         [0016]    In a first step  82  of the flow chart  78 , the simulator is run with selected fluid properties and selected flow rates. A temperature profile is measured with the DTS  30  in the second step  86 . In a third step  90  the mathematical model is run and a temperature profile is calculated. The fourth step  94  involves comparing the measured temperature profile to the calculated temperature profile. In the fifth step  98 , a decision is made as to whether the model is calibrated based on whether the measured and calculated temperature profiles match. If they do not match, the variables of the model are iterated and temperature profiles recalculated until they do match. Step  102  permits iteration of the foregoing steps until all desired operational conditions have been simulated and correlated with the mathematical model. 
         [0017]    Referring to  FIG. 4 , a process for diagnosing a completion operation by comparison to the mathematical model or the simulator is shown by flow chart  106 . In a first step  110  of the process the completion liner  10  is operated in a completion operation as schematically illustrated in  FIG. 1 . A temperature profile is measured with the DTS  30  in a second step  114 . In a third step  118  the simulator is analyzed to find parameters that result in a matching temperature profile to that measured in the completion operation. Alternately, the model can be analyzed to find variables that result in a matching profile to that measured in the completion operation. A fourth step  122  attributes fluid properties and flow rates at matched settings from the model or simulator to actual completion operational conditions. With such knowledge the operator of the completion can perform the fifth step  126  and make adjustments to the completion, such as, through closure of valves, for example, to increase longevity of the completion and total production recoverable therefrom, as discussed above. Step six  130  allows the foregoing steps to be repeated over time as differences in the measured temperature profile change. Additionally, when changes to the measured temperature profile occur over time the process allows for diagnosing what has changed, i.e. fluid density, fluid viscosity, fluid oil to water to gas ratios or flow rates, so that appropriate corrective actions can be taken. 
         [0018]    While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.