U.S. patent application number 16/071976 was filed with the patent office on 2019-02-21 for method and system for automated adjustment of drilling mud properties.
This patent application is currently assigned to SHELL OIL COMPANY. The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Patricia ASTRID, Jan-Jette BLANGE, Svetlana Viktorovna HAGERAATS-PONOMAREVA, Timothy Engelbertus SCHUIT.
Application Number | 20190055797 16/071976 |
Document ID | / |
Family ID | 55229605 |
Filed Date | 2019-02-21 |
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United States Patent
Application |
20190055797 |
Kind Code |
A1 |
ASTRID; Patricia ; et
al. |
February 21, 2019 |
METHOD AND SYSTEM FOR AUTOMATED ADJUSTMENT OF DRILLING MUD
PROPERTIES
Abstract
Drilling mud properties in a mud recirculation system (13) of an
oil and/or gas well drilling assembly (1) are automatically
adjusted by an automated mud treating assembly (20,25) that is
governed hierarchal primary and secondary optimization and control
loops (30,31) that continuously keep the density, viscosity, pH and
other mud properties within specifications set by a model-based
tertiary optimization and control loop to ensure that the mud
properties will lead to sufficient drilled cutting transport,
borehole stability, drill bit hydraulics, and minimum friction
torque and drag.
Inventors: |
ASTRID; Patricia;
(Amsterdam, NL) ; BLANGE; Jan-Jette; (Rijswijk,
NL) ; HAGERAATS-PONOMAREVA; Svetlana Viktorovna;
(Rijswijk, NL) ; SCHUIT; Timothy Engelbertus;
(Rijswijk, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
HOUSTON |
TX |
US |
|
|
Assignee: |
SHELL OIL COMPANY
HOUSTON
TX
|
Family ID: |
55229605 |
Appl. No.: |
16/071976 |
Filed: |
January 23, 2017 |
PCT Filed: |
January 23, 2017 |
PCT NO: |
PCT/EP2017/051329 |
371 Date: |
July 23, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 44/00 20130101;
E21B 21/106 20130101; E21B 21/062 20130101; E21B 49/0875 20200501;
E21B 21/06 20130101; E21B 21/08 20130101 |
International
Class: |
E21B 21/06 20060101
E21B021/06; E21B 21/10 20060101 E21B021/10; E21B 21/08 20060101
E21B021/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 25, 2016 |
EP |
16152522.5 |
Claims
1. A method for automated adjustment of drilling mud properties in
a mud recirculation system of a rig for drilling an underground
wellbore, the method comprising inducing hierarchal primary and
secondary optimization and control loops to adjust injection rates
of mud additives into a circulated mud stream flowing through an
automated mud treating assembly, to continuously keep mud
properties, comprising density, viscosity, pH and optionally other
mud properties, within specifications set by a model-based tertiary
optimization and control loop.
2. The method of claim 1, wherein the primary optimization and
control loop governs opening and closing of additive injection
control valves of the automated mud treating assembly to meet
injection rates of each additive set by set by the secondary
optimization and control loop that is connected to the tertiary
optimization and control loop that determines the appropriate
ranges or setpoints for the mud properties in order to meet
multiple operational objectives, such as maximizing cutting
transport capabilities of the drilling mud and maintaining wellbore
mechanical stability.
3. The method of claim 1, wherein the mud properties are measured
by a sensor assembly that measures the mud properties of the mud in
the mud recirculation system at the rig upstream and/or downstream
of the automated mud treating assembly.
4. The method of claim 3, wherein the sensor assembly comprises an
upstream sensor assembly comprising primary and secondary untreated
mud flux property sensors for monitoring the properties of the
untreated mud flowing from a cuttings removal system to the
automated mud treating assembly, wherein the primary untreated mud
flux property sensor is arranged in the mud recirculation system
between the secondary untreated mud flux property sensor and the
mud treating assembly.
5. The method of claim 1, wherein: the primary, secondary and
tertiary optimization and control loops operate at different time
scales and hierarchies; the tertiary optimization and control loop
is the master of the secondary optimization and control loop and
operates at the highest time scale or lower sampling rate; and the
secondary optimization and control loop is governed by the tertiary
optimization and control loop and operates at the lower time scale
or higher sampling rate than the tertiary optimization and control
loop but higher time scale and lower sampling rate than the primary
optimization and control loop which is governed by the secondary
optimization and control loop.
6. The method of claim 4, wherein the sensor assembly further
comprises a downstream sensor assembly comprising primary and
secondary treated mud property sensors for measuring at least one
of the group consisting of: density, viscosity, pH and other
properties,. of the treated mud in the mud recirculation system at
the rig downstream of the mud treating assembly, wherein the
primary treated mud flux property sensor is arranged in the mud
recirculation system between the mud treating assembly and the
secondary treated mud property sensor; and wherein: the primary
optimization and control loop is connected to a sensor assembly
that measures the actual injection rate of each additive in the
automated mud treating assembly; the secondary optimization and
control loop is connected to the sensor assembly that measures the
primary untreated and treated mud properties; the tertiary
optimization and control loop is connected to the primary untreated
mud sensor assembly and optionally to the secondary untreated mud
sensor assembly.
7. The method of claim 4, wherein the primary treated mud flux
property sensor forms part of the secondary optimization and
control loop and the secondary treated mud flux property sensor
forms part of the tertiary optimization and control loop.
8. The method of claim 1, wherein the tertiary optimization and
control loop comprises an optimization module that determines the
ranges or the setpoints of the primary treated mud properties given
the objective functions of the tertiary optimization and control
loop such as ensuring sufficient cutting transport, wellbore
mechanical stability and estimates of: a) drill string torque and
drag; b) borehole stability and permeability; c) size, volume,
weight, density and composition of drill cuttings; and d) downhole
mud velocity, pH, viscosity, density and composition.
9. The method of claim 8, wherein the ranges of the mud property
values as determined by the optimization module are included as the
desired ranges to be honored by a multivariable control algorithm
in the secondary control loop.
10. The method of claim 9, wherein the multivariable control
algorithm is a Model Predictive Controller (MPC) algorithm that
casts the multivariable control problem as an optimal control
problem with an objective function of minimizing the deviation of
the primary treated mud properties from the desired ranges given
the minimum and maximum amount of additives to be added at each
cycle and the models between mud properties to be controlled and
additives as well as the drilling and mud flux circulation
rates.
11. The method of claim 10, wherein the multivariable control
algorithm is provided with models identifying mathematical
relationships between the additives, mud properties and measured
variations in drilling rates that affect variations in drill
cuttings concentration.
12. A system for automated adjustment of drilling mud properties in
a mud recirculation system of a rig for drilling an underground
wellbore, the system comprising hierarchal primary and secondary
optimization and control loops to adjust injection rates of mud
additives into a mud circulation conduit in an automated mud
treating assembly, arranged to continuously keep mud properties,
comprising density, viscosity, pH, within specifications set by a
model-based tertiary optimization and control loop.
13. The system of claim 12, wherein the primary optimization and
control that governs opening and closing of the additive control
valves of the automated mud treating assembly, to meet the
injection rates of each additive set by set by the secondary
optimization and control loop that is connected to the tertiary
optimization and control loop that determines the appropriate
ranges or setpoints for the mud properties in order to meet
multiple operational objectives, such as maximizing cutting
transport capabilities of the drilling mud and maintaining wellbore
mechanical stability.
14. The system of claim 12, wherein the system comprises a sensor
assembly that measures the mud properties of the mud in the mud
recirculation system at the rig upstream and/or downstream of the
automated mud treating assembly.
15. The system of claim 12, wherein the mud treating assembly
comprises an additives and mud mixing tank, the size of which is
determined by two aspects: the minimum residence time required by
the characteristics of the drilling mud to ensure a homogeneous
mixture when additives are added; and the balance between the
response time required by the secondary multivariable control loop
to bring the properties of the primary untreated mud to the desired
values or ranges while ensuring that the addition of the additives
as the result of the controller's actions does not lead to major
fluctuations in the steady state or transient values of the primary
treated and secondary untreated mud properties.
16. The system of claim 12, wherein said hierarchal primary and
secondary optimization and control loops are additionally arranged
to continuously keep other mud properties within specifications set
by the model-based tertiary optimization and control loop.
17. The method of claim 1, wherein additionally inducing said
hierarchal primary and secondary optimization and control loops to
continuously keep other mud properties within specifications set by
the model-based tertiary optimization and control loop.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and system for
automated adjustment of drilling mud properties in a mud
recirculation system of a rig for drilling an underground
wellbore.
BACKGROUND OF THE INVENTION
[0002] During drilling of underground wellbores for the production
of crude oil and/or natural gas a drilling fluid, generally known
as drilling mud, is circulated in downward direction through the
interior of the drill string and then in upward direction through
the surrounding annulus to lift drill cuttings to the surface, to
clean and cool the drill bit, to stabilize the borehole, to
lubricate the rotating drill string and to provide hydrostatic head
for preventing well kicks.
[0003] At the wellhead the drill cuttings are removed from the
drilling mud in a mud cleaning assembly and the mud volume is
adjusted by adding fresh mud and the composition of the re-injected
mud is adjusted by adding mud additives in a mud treatment assembly
to generate desired mud properties, such as mud density, viscosity
and pH.
[0004] A fluid handling system is described in WO 97/42395 A1,
specifically for underbalanced drilling operations. A control unit
determines or computes values of a number of operating parameters
of the fluid handling system and controls the operation of the
various devices based on such parameters according to programs and
models provided to the control unit. The control unit, which
receives signals from sensors, is coupled to the various devices in
the system for controlling the operations of the devices, including
control valves. The control unit periodically or continually
determines the required drilling fluid mix as a function of one or
more of the selected operating parameters and operates a control
valve to discharge a correct amount of additive materials to obtain
the desired mix.
[0005] At the moment, there is no integrated solution utilizing a
combination of integrated hardware and software that makes use of
the measurement data to predict the downhole condition and control
the mud properties in order to mitigate or avoid operational
issues.
[0006] There is a need for an improved mud additive injection
control system and method which overcome the drawbacks of the prior
art.
[0007] Furthermore there is a need for a more efficient mud system
management that minimizes waste and use of materials used to treat
the mud and minimize operational downtime, due to for example a
stuck drill pipe and/or drill pipe vibration, and operational
issues, such as lack of well control and/or borehole instability
due to the failure of keeping the mud properties at the desired
specification.
SUMMARY OF THE INVENTION
[0008] In one aspect of the invention, there is provided a method
for automated adjustment of drilling mud properties in a mud
recirculation system of a rig for drilling an underground wellbore,
the method comprising inducing hierarchal primary and secondary
optimization and control loops to adjust injection rates of mud
additives into a circulated mud stream flowing through an automated
mud treating assembly, to continuously keep mud properties,
comprising density, viscosity, pH and optionally other mud
properties, within specifications set by a model-based tertiary
optimization and control loop.
[0009] In another aspect of the invention, there is provided a
system for automated adjustment of drilling mud properties in a mud
recirculation system of a rig for drilling an underground wellbore,
the system comprising hierarchal primary and secondary optimization
and control loops to adjust injection rates of mud additives into a
mud circulation conduit in an automated mud treating assembly,
arranged to continuously keep mud properties, comprising density,
viscosity, pH and optionally other mud properties, within
specifications set a model-based tertiary optimization and control
loop.
[0010] These and other features, embodiments and advantages of the
method and system as proposed herein are described in the
accompanying claims, abstract and the following detailed
description of non-limiting embodiments depicted in the
accompanying drawing, in which description reference numerals are
used which refer to corresponding reference numerals that are
depicted in the drawing.
[0011] Objects and other features depicted in the figure and/or
described in this specification, abstract and/or claims may be
combined in different ways by a person skilled in the art.
BRIEF DESCRIPTION OF THE DRAWING
[0012] The systems and methods will be described hereinafter by way
of example in more detail with reference to FIG. 1, which is a
schematic representation of a drilling assembly provided with an
automated mud additive injection control system. No limitations are
intended to the details of construction or design herein shown,
other than as described in the claims below.
DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENT
[0013] A method and system are proposed for automated adjustment of
drilling mud properties in a mud recirculation system. Such mud
recirculation system may form part of a drilling assembly for
excavating an underground wellbore. The mud recirculation system
may be applied on a rig for drilling an underground formation.
[0014] In one proposed method for automated adjustment of drilling
mud properties in a mud recirculation system of a rig for drilling
an underground wellbore, hierarchal primary and secondary
optimization and control loops are induced to control an automated
mud treating assembly which injects additives that continuously
keep density, viscosity, pH and other mud properties within the
specifications. Rather than that these specifications are set by an
operator, a tertiary model-based optimization and control loop may
be run to set the specifications.
[0015] This may be implemented by three nested optimization and
control loops as follows: the tertiary optimization and control
loop determines specifications for mud properties comprising
density, viscosity, pH and optionally other mud properties on the
basis of a model which optimizes desired downhole properties of the
injected mud for assessed downhole drilling conditions. These mud
property specifications are fed as setpoints to the secondary
optimization and control loop, which determines the required
additives to achieve the desired setpoint mud properties. The
required additives as computed by the secondary loop then become
the setpoints for the primary control loops, which open additive
injection valves to achieve the required additives. The tertiary
optimization and control loop may also determine setpoints of flow
rate of the circulated mud stream, which may be fed directly to the
pump control system without intervention by the secondary and
primary optimization and control loops.
[0016] The mud properties may be measured by a sensor assembly that
measures density, viscosity, pH and/or other properties of the mud
in the mud recirculation system at the rig upstream and/or
downstream of the automated mud treating assembly, which sensor
assembly may comprise an upstream sensor assembly comprising
primary and secondary untreated mud property sensors for monitoring
the properties of the untreated mud flowing from a cuttings removal
system to the automated mud treating assembly. The primary
untreated mud flux property sensor may be arranged in the mud
recirculation system between the secondary untreated mud flux
property sensor and the mud treating assembly.
[0017] The automated mud treating assembly may comprise additive
injection control devices, suitably injection control valves, that
are controlled by the primary optimization and control loop to meet
the injection rates of each additive set by set by the secondary
optimization and control loop that is connected to the tertiary
optimization and control loop that determines the appropriate
ranges or setpoints for density, viscosity, pH and other mud
properties in order to meet multiple operational objectives, such
as maximizing cutting transport capabilities of the drilling mud
and maintaining wellbore mechanical stability.
[0018] Optionally, the primary, secondary and tertiary optimization
and control loops operate at different time scales and hierarchies,
whereby: [0019] the tertiary optimization and control loop is the
master of the secondary optimization and control loop and operates
at the highest time scale or lower sampling rate; and [0020] the
secondary optimization and control loop is governed by, also called
the slave of, the tertiary optimization and control loop and
operates at the lower time scale or higher sampling rate than the
tertiary optimization and control loop but higher time scale and
lower sampling rate than the primary optimization and control loop
which is governed by, also called the slave of, the secondary
optimization and control loop.
[0021] The tertiary optimization and control loop may comprise an
optimization module that determines the ranges or the setpoints of
the primary treated mud properties given the objective functions of
the tertiary optimization and control loop such as ensuring
sufficient cutting transport, wellbore mechanical stability and
given estimates of:
[0022] a) drill string torque and drag;
[0023] b) borehole stability and permeability;
[0024] c) size, volume, weight, density and composition of drill
cuttings; and
[0025] d) downhole mud velocity, pH, viscosity, density and
composition.
[0026] The ranges of the mud property values as determined by the
optimization module of the tertiary loop may suitably be included
as the desired ranges to be honored by a multivariable control
algorithm in the secondary control loop. The multivariable control
algorithm suitably provides a setpoint for the injection rate of
each one of the injected mud additives. The multivariable control
algorithm may be a Model Predictive Controller (MPC) algorithm that
casts the multivariable control problem as an optimal control
problem with an objective function of minimizing the deviation of
the primary treated mud properties from the desired ranges given
the minimum and maximum amount of additives to be added at each
cycle and the models between mud properties to be controlled and
additives as well as the drilling and mud flux circulation rates,
which casts the mud properties control problem into a multivariable
optimization solution with constraints over a selected time horizon
that take into account the amount of time required for the mud to
be circulated through the borehole and back to the drilling rig at
earth surface.
[0027] The multivariable control MPC algorithm may be provided with
models identifying mathematical relationships between the
additives, mud properties and measured variations in drilling rates
that affect variations in drill cuttings concentration.
[0028] The proposed method may be implemented in a system for
automated adjustment of drilling mud properties in the mud
recirculation system.
[0029] An example of an implementation of an automated mud
treatment system and method is illustrated with reference to FIG.
1. FIG. 1 shows a drilling assembly 1 comprising a drill bit 2 that
is rotated by a drill string 3 as illustrated by arrows 4 to
excavate an underground borehole 5.
[0030] Drilling mud 6 is pumped down through the drill string 3 as
illustrated by arrows 7 and up through the surrounding annulus 8 as
illustrated by arrow 9 to lift drill cuttings 10 to the earth
surface 11, where the drill cuttings are removed from the returned
mud 6 in a mud shaker and filter assembly 12.
[0031] The cleaned mud 6 is subsequently transported via a mud
recirculation conduit 13 and a top drive swivel 14 back into the
drill string 3. Even though the mud is recirculated, and as such
there is strictly speaking no begin and end to the circuit, for the
purpose of interpretation of terms such as "upstream",
"downstream", and for defining the order in which certain parts of
equipment are configured relative to each other in the mud
circulation system, the mud share and filter assembly 12 is taken
to be "the end" of the mud recirculation cycle, which is considered
to be the most "downstream" end of the cycle. The most "upstream"
end of the cycle is the transition from the mud share and filter
assembly 12 into the mud recirculation conduit 13.
[0032] The mud recirculation conduit 13 is connected to a mud
mixing tank 15 in which additional mud can be added from a mud tank
16 and in which the mud is mixed by a mixer 17 to homogenize the
mud 6 before it is pumped back into the drill string 3 by a mud
pump assembly 17,18. The mud mixing tank 15 may be referred to as
untreated mud mixing tank 15, as it is located upstream of a mud
treating assembly 20 to which the mud recirculation conduit 13 is
furthermore connected. In this mud treating assembly 20 mud
additives 21-24 are injected into the mud, to ultimately adjust mud
properties, such as density, viscosity and pH.
[0033] The mud treating assembly 20 is suitably equipped with an
automated additive injection control system 25 that automatically
adjusts the injection rates of each of the mud additives 21-24 on
the basis of measurements of the properties of untreated mud 6
upstream of the treating assembly 20 by primary and secondary
untreated mud property sensors 26-27 and measurements of the
treated mud 6 downstream of the treating assembly 20 by primary and
secondary treated mud property sensors 28-29. An untreated mud
mixing tank 15 may be arranged in the mud recirculation system 13
between the primary and secondary untreated mud property sensors
26-27.
[0034] The primary and secondary untreated and treated mud property
sensors 26-27 and 28-29 form part of a hierarchical closed loop
control system which contains two closed loops 30-31, where loop 30
is configured as a primary or master control loop and the other
loop 31 is configured as a secondary or slave control loop. Both
closed loop 30-31 make use of assemblies of substantially similar
mud property sensors 26-29, located in predefined positions
upstream and downstream of the mud treating assembly 20, providing
necessary data for mud property monitoring and control.
[0035] The automated mud treating system 25 may comprise an
additive injection optimization module comprising a computer
programmed with algorithms known as Wells Advanced Kernels (WAKs)
and a mathematical optimization module to provide the secondary
multivariable control loop (for example the MPC alogrithm) with
specifications for mud properties such as density, viscosity, pH
and optionally other mud properties based on advanced drilling
parameters modelling and real time data. Setpoints for circulation
flow rate, which may also be computed, may be fed directly to the
rig mud pump assembly 17,18. Given the specifications for the mud
properties, the secondary multivariable control loop then computes
the required mud additives 21-24. The required mud additives 21-24
as computed by the secondary optimization and control loop become
the set points for the primary closed loop control system 30, which
adjusts the valve openings accordingly to meet the setpoints of
each of the mud additives 21-24.
[0036] The automated drilling mud treating system 20, 25 is able to
adjust mud properties more accurately than manually controlled
drilling fluid additive systems that may still be present on the
drilling rig 33 for start-up and/or as a back-up in case of
malfunctioning of the automated mud treating system 20,25. The
automated additive injection control system 20,25 automatically
adjusts during at least part of the drilling operations the
drilling fluid additive injection rates to adjust the mud
properties to a desired set-point based on a predefined reference
signal.
[0037] The mud treating system 20 is arranged in an additives and
mud mixing tank 34, which is designed in such a way to ensure
sufficient mixing quality and appropriate response time to bring
the mud properties back to a desired specification, and a set of
physical actuators, such as additive injection pumps and control
valves (not shown), for automatic addition of the mud additives
21-24. The size of the mixing tank 34 may suitably be determined by
taking into account the following aspects: [0038] the minimum
residence time required by the characteristics of the drilling mud
to ensure a homogeneous mixture when additives are added; and
[0039] the balance between the response time required by the
secondary multivariable control loop to bring the properties of the
primary untreated mud to the desired values or ranges while
ensuring that the addition of the additives as the result of the
controller's actions does not lead to major fluctuations in the
steady state or transient values of the primary treated and
secondary untreated mud properties.
[0040] The flow rates of the mud additives 21-24 into the additives
and mud mixing tank 34 are regulated by the automated additive
injection control system 25, which uses the data generated by the
mud flux property sensor assemblies 26,27 about the untreated mud 6
returned from the borehole 5 is compared to reference signals or
desired specifications of the mud properties, which can originate
from operators or from an automatic set point optimization module
based on the Wells Advance Kernel (WAK) prediction. Any deviations
(error signals) from the desired setpoints will trigger the control
algorithm to compute required amount of additives 21-24 to be added
to the mud 6 and these computations are sent to the control valves
of the mud treating assembly 20, 25.
[0041] The automated mud treating system 20,25 may furthermore be
provided with an MPC algorithm, which casts the mud properties
control problem into a multivariable optimization solution with
constraints over a certain time horizon to take into account the
amount of time required for the mud 6 to be circulated through the
borehole 5 and back to the surface 11. The MPC algorithm is a
control approach that takes the time horizon and input constraints
into account.
[0042] The MPC algorithm may be provided with models identifying
mathematical relationships between the additives, mud properties,
and also measured disturbances such as variations in drilling rates
that affect variations in drill cuttings 10 concentration. The
effects of disturbances can change the relationship between the
additives 21-24 and mud properties, which may be automatically
corrected by the MPC algorithm.
[0043] There are two options to correct the models in the MPC
algorithm: [0044] I) One option is to correct the model by adding a
filter, for example a Kalman Filter, that corrects and updates the
model continuously based on measurement data. [0045] II) Another
option is to use an automatic model-rebuilding mechanism if the
amount of updates from the Kalman Filter is too big. The automatic
model-rebuilding mechanism is carried out by varying the additive
signals systematically in such a way that meaningful mathematical
relationships can still be derived without disturbing the drilling
operations. The input signals and measured mud properties resulting
from this systematic variation is then used to derive a new model
for the control algorithm.
[0046] The required mud property specification and associated
additive injection setpoints in the automated mud treating system
20,25 can be updated automatically by means of an optimization
algorithm. Given the mud weight and the viscosity profile of the
mud, the Wells Advanced Kernels (WAKs) may provide a prediction of
the cutting transport state, the equivalent circulating density,
and, optionally, the torque and drag profile along the borehole 5
and, also optionally, the elastic borehole stability. The
mathematical models between the mud properties and these parameters
can be derived by feeding the kernels with mud property values and
fit models between the mud properties and the cuttings transport,
drill string torque and drag and borehole stability. Given the
selected mathematical model(s) and operational objective(s), such
as maximize borehole cleaning and maximize borehole stability and
applying a linear or nonlinear optimization algorithm, the
appropriate setpoints for the mud additive injection rates can be
derived automatically from the selected model(s).
[0047] Therefore, the method and system described herein are well
adapted to attain the ends and advantages mentioned as well as
those that are inherent therein.
[0048] The particular embodiments disclosed above are illustrative
only, as the present invention may be modified, combined and/or
practiced in different but equivalent manners apparent to those
skilled in the art having the benefit of the teachings herein.
[0049] It is therefore evident that the particular illustrative
embodiments disclosed above may be altered, combined and/or
modified and all such variations are considered within the scope of
the present invention as defined in the accompanying claims.
* * * * *