APPLICATION OF LINEAR NETWORK SCHEDULES FOR PLANNING AND MANAGEMENT OF CONSTRUCTION AND INSTALLATION WORKS IN WELL DRILLING

P. I. STEPANOV

(Presented by the scientific seminar of the Department of Industrial Economics and Enterprise Organization)

In recent years, major successes have been achieved in the organization of construction and installation work through the introduction of block construction of drilling rigs, the installation and dismantling of equipment, its transportation in unassembled form, the use of masts instead of derricks, and so forth. At the same time, an analysis of the technical and economic indicators of these works shows that geological production organizations carrying out prospecting and exploration work both for solid minerals and for oil and gas possess substantial reserves for further improvement in the organization of production of construction and installation works.

Especially large reserves exist in the organization of labor among workers of construction and installation crews. Studies have established that, in improving the organization of labor and production, a significant effect is obtained from the use of graphical methods in the form of linear network schedules.

At present, the most widely used are linear schedules and calendar plans [3]. These schedules reflect the time required to perform the work, indicating the necessary quantity of resources (workers, equipment, materials, etc.). The main drawback of linear schedules is that they do not reflect the interrelationships between the elements of the work, nor do they indicate the names of the executors. These shortcomings increase as the system modeled in the schedule becomes more complex.

These shortcomings lead to the fact that, when work is performed—in particular installation and dismantling work—various kinds of inconsistencies arise, resulting in losses of working time due to waiting, coordination, and so on. Thus, for example, when conducting a workday time study in a construction and installation crew headed by Comrade V. K. Anisimov from the Aleksandrovsk Oil Exploration Expedition, it was found that individual workers were engaged in productive work from 74 to 96% of their working time. The remaining time was idle due to waiting for work, transport, and also because of overregulated breaks. Overall, according to the time-and-motion data, productive time in this crew amounted to about 77% of the standard working-time budget.

The use of linear network schedules instead of linear ones makes it possible to significantly reduce unproductive expenditures of working time. Linear network schedules consist of a network schedule and schedules of resource utilization. The network schedule represents in graphical—

in schematic form, is a model of construction-installation and dismantling work and transportation, taking into account the logical state of the interconnections between elements. Load schedules show the distribution of performers, means of transport, equipment, and material-and-technical supply, and have a linear form. What distinguishes them from the linear schedules described above is that an entirely different method is used in their construction. If in linear schedules resources are distributed among work elements, then in load schedules, on the contrary, work elements are distributed among resources. Such a method of graphically representing the work-production plan is of very great importance in creating rhythmic conditions for its execution; it makes it possible to load performers more correctly, taking account of their qualifications and personal qualities, and also to load the equipment used more evenly.

The application of linear-network schedules in the dismantling, transportation, and installation of rigs in the Korbalikhinskaya GRP of the Rudno-Altai Expedition of the West Siberian Geological Administration created conditions for fulfilling output standards at 139–145%. In our opinion, the application of linear-network schedules in rig construction in petroleum-exploration expeditions will make it possible to eliminate unproductive expenditures of working time and, on this basis, to increase labor productivity in drilling operations as a whole.

When applying network schedules for the planning, organization, and management of individual types of geological work, the adopted method of distributing resources among the elements of the schedule is of great importance. Resource distribution can be carried out both on the schedule itself and on additionally constructed resource-load schedules.

Studies have established that it is better to distribute resources on additionally constructed load schedules for various resources. In this case, the visual clarity of the graphical representation of the work is significantly improved, the time expenditures for distributing resources among the elements of the schedule are reduced, taking into account the uniformity of their use, control over the progress of the work is greatly simplified, and, finally, the process of revising the original work-execution plan is facilitated when production situations arise that disrupt the course of the work (illness or dismissal of performers, equipment breakdown, untimely delivery of material assets, etc.).

Figure 1 shows an enlarged linear-network schedule of installation-and-dismantling work. The network schedule, being a model of the work, may be standard under certain production-and-technical factors and terrain-relief conditions. It is constructed not to a time scale, and it reflects the names of the work elements as well as the total labor expenditures for the performance of each of them.

After the network schedule has been constructed, a load schedule is drawn up for the performers—members of the construction-and-installation crew, or members of the drilling crew in the absence of a specialized rig-construction crew—and also a load schedule for the means of transport. The load schedules for performers and means of transport should be constructed simultaneously. Very often the distribution of work among performers depends on the availability and necessity of uniform loading of the means of transport. Load schedules are constructed to a time scale; for this purpose time in hours, days, or months is plotted along the abscissa axis.

The procedure for constructing load schedules is as follows. The first column gives a surname-by-surname list of performers, as well as a list of means of transport by type.

The distribution of work among performers and means of transport is carried out by the method of enumerating variants, taking into account logical depen-

a) Network schedule

b) Workload schedule for the drilling crew

c) Transport utilization schedule

Fig. 1. Linear network schedule of dismantling and installation operations. Rig ZIF–650A; derrick height 18 m; collapsible heated shelter. Legend: 0, 1—dismantling the drilling string; 1, 2—pulling the casing pipes; 2, 4—dismantling the derrick; 2, 3—disconnecting the power line; 2, 7—transporting the tools; 2, 11—backfilling pits; 2, 12—grading the new site; 2, 17—sheathing the settling tanks; 4, 5—dismantling the heated shelter; 4, 8—transporting the heated shelter; 5, 6—transporting the rig; 6, 13—installing the drilling unit; 13, 14—installing the heated shelter; 14, 15—installing the derrick; 3, 9—dismantling the cable; 9, 10—laying the cable at the new site; 10, 18—connecting the power line to the drilling unit; 13, 16—installing the PO-49; 15, 19—acceptance of the rig; 19, 20—eliminating deficiencies; 20, 21—spudding the well. The numbers above the operations in the network schedule denote labor expenditures in man-hours.

dependencies reflected in the network schedule and mean that any subsequent operation may begin after the preceding one has been completed, while operations located on parallel paths may be performed simultaneously.

The distribution of work among performers is carried out with regard to the qualifications, specialization, and personal qualities of the performers. The work distributed among performers and vehicles is shown on workload schedules by a straight line, with points or other marks indicating the moment of the beginning and end of the execution of its individual elements. Above the line the work index is shown in accordance with the network schedule, i.e., the numbers of the initial and final events that bound the individual work operation are indicated. The time required for each performer to carry out this operation may also be shown next to the index.

The material and technical supply schedule shows the names of the required material assets needed for carrying out the installation and dismantling operations, spudding and drilling the well, and the dates of their delivery.

In production activity, situations sometimes arise in which the rhythmic execution of work is disrupted, for example because performers are absent due to temporary incapacity for work or dismissal—

...of performers, breakdowns of transport vehicles, etc. In such adverse situations, the workload schedules for performers and transport vehicles should be restructured with account taken of the actual production situation that has developed, while the network schedule should be left unchanged. The network schedule serves, as it were, as a visual aid reflecting the logical interconnection among the elements and the total labor inputs.

When a linear network schedule is available, the work of monitoring the progress of erection-dismantling and construction-assembly operations is simplified. Here there is no need to hold daily assignment meetings or for the brigade leader to issue a task to a worker after completion of the preceding job, since the worker or group of workers themselves determine from the schedule what subsequent job they must perform.

The time expenditures for carrying out individual operations are taken from handbooks of unified time (output) standards for drilling operations and from unified time standards for construction-assembly operations in drilling [1, 2].

If standards are lacking for certain operations, and also where the specific working conditions differ greatly from the conditions for which the standards were compiled, the time standards should be calculated by the formula

\[ t_{\text{n.vr}}=\frac{3t_{\min}+2t_{\max}}{5}, \]

where \(t_{\text{n.vr}}\) is the calculated time standard, with probabilistic estimates taken into account;
\(t_{\min}\) is the minimum time required to perform the given operation;
\(t_{\max}\) is the maximum time required to perform the operation, taking into account the influence of certain adverse factors.

The maximum and minimum necessary time expenditures for carrying out the work are determined with account taken of the opinions of the performers and brigade leaders, as well as previous work experience.

Thus, the use of linear network schedules in derrick-construction and erection-dismantling work makes it possible to:

create greater regularity and purposefulness in carrying out the work;

establish, in a visual form, specific assignments for each performer and for technical equipment for an hour, a working day, and the entire period of performance of the work, taking into account continuity and uniformity in the workload of each of them;

distribute the work among performers not only with account taken of their qualifications, but also of personal qualities and the relationships that have developed among them;

when adverse production situations arise that cause deviations from the original plan, quickly, on a scientific basis, redistribute resources on the workload schedules, taking into account the logical interconnections reflected in the network model;

establish effective control over the work of each performer, the transport vehicles, and the use of other resources;

increase the discipline and responsibility of each performer for the timely execution of the assigned operation, since he knows that the timely completion of all the work provided for by the schedule depends on it.

References

1. Unified Time Standards for Construction-Assembly Operations in Drilling. Second edition. Moscow, 1965.

2. Unified Time Standards for Drilling Exploratory, Structural-Prospecting, and Mapping Wells. Gostoptekhizdat, 1963.

3. M. A. Saakov. Construction and Assembly of Drilling Rigs. Moscow, 1965.