Drilling holes serves a multitude of purposes, with each objective tailored to specific needs. Take, for instance, the following scenarios:
- Insertion and Storage: Creating a hole facilitates the insertion of objects for storage or disposal.
- Access Routes: Holes are often drilled to establish pathways through materials, such as shafts and tunnels.
- Information Extraction: Valuable information can be extracted directly from the drilling process, including tests, measurements conducted within the hole, or samples retrieved from the formations.
- Resource Extraction: Holes play a crucial role in extracting resources such as oil, gas, steam, water, and dissolved minerals.
The term "drilling objective" encapsulates the purpose behind hole creation, consisting of four integral components:
- Directives: These instruct the driller on the "what" and "why" of the task at hand.
- Criteria: Standards delineate measurements, drilling angles, and logging prerequisites for the driller.
- Contextual Factors: Conditions lay out the specifics of how, when, and where these standards are applicable.
- Verification Methods: Checks provide drillers with methodologies to ensure strict adherence to established standards.
Clarity is paramount in the "Directives," ensuring that the driller comprehends their instructions. The task cannot be executed effectively without a comprehensive understanding of the goal. For instance: "Conduct exploratory drilling to obtain data about formations and their locations; procure chip samples for subsequent laboratory analysis."
"Criteria" are precise specifications guiding drilling operations. Some standards are universally applicable, necessitating unwavering compliance. They serve as benchmarks for the task's execution. Examples include:
- Proximity Requirement: The hole's location should deviate no more than 0.5 meters (18 inches) from the designated point.
- Depth Mandate: Drill to a depth of precisely 100 meters (300 feet).
- Diameter Stipulation: The minimum hole diameter is 125 mm (5 inches).
- Verticality Emphasis: Maintain the hole's inclination within 3 degrees of vertical throughout.
- Sampling Consistency: Gather samples at 1-meter (3-foot) intervals.
- Logging Accuracy: Drilling logs must precisely document formation changes within 0.2 meters (8 inches) of their actual position.
"Conditions" establish the contextual framework for adhering to standards, accounting for factors such as site access, weather conditions, and operational hours. Consider the following examples:
- Temporal Constraint: Limit drilling activities to the dry season.
- Daylight Restriction: Confine drilling operations to daylight hours.
- The hole is to be stabilised and kept open for logging after drilling is completed.
- Fireighting equipment will be carried and maintained in good working condition.
Examples of Checks made to ensure that the required standards are being, or have been, met include:
- Hole verticality may be checked using a wire line survey method
- The position of the changes in formation may be checked by electric logging
- Sample volume and variation will be randomly checked throughout the program.
The examples given above should help to understand how drilling objectives should be documented. If drilling contracts were writen with these guidelines in mind, there would be fewer problems, as all on-site personnel would have thorough knowledge of the requirements.
The driller is primarily concerned with the three objectives highlighted in Figure 1. He should recognise that other objectives have contributed to this, but must achieve his objectives while keeping the other objectives in mind. As the diagram shows, the drilling
process conirms some of the contributing objectives and clearly they are critical ones.
With the advances in technology that have taken place in the drilling industry, it is now possible to drill a hole in any material, get the required information from it, and achieve the drilling objectives.
But each objective can be achieved only if it is matched with the appropriate skills, equipment, tools, and materials to do the job. To ensure that the driller satisies the job requirements, he must be able to select and use the most suitable drilling equipment, along with
the best hole making and stabilising method.
If the driller has done this while recognising what is happening, he can be reasonably sure of completing the job successfully. However, all these considerations cost money. If a client asks for some particular result or information, a driller must be able to explain:
• what is involved in achieving the result or gaining the information
• how much the required skills and equipment will cost
• how long it will take.
Drilling objectives are only one of a number of objectives all contributing to a project objective.
Used in conjunction with the driller’s knowledge, skills, and equipment, almost any objective can be achieved, provided that the objective is clearly and concisely writen. This will ensure that all personnel have a thorough knowledge of the requirements. The driller can then use his equipment and skills to carry out
an eicient and economical drilling operation.