Getting into the Zone
Some Petroleum Engineers are said to have the touch while others are called lucky, but for those who know better, it’s a demanding yet rewarding profession reliant on appreciating the complexities of creation.
Preamble: As much as petroleum engineering is rapidly evolving, highly technical, and not for those who may have difficulty with stress, getting your arms around the-ever-changing-geology of mother earth is a talent and skill, and commitment, that is learned and practiced over long periods of time. Some Petroleum Engineers are said to have the touch while others are called lucky, but for those who know better, it’s a demanding yet rewarding profession that appreciates the complexities of creation and who have developed the intellect of how best to discover and exploit the much needed resources. This short blog cannot address all what’s involved to find hydrocarbon deposits between the layers of the onion, nor describe ways to harvest the minerals to any degree of specificity, but I can recommend viewing a most informative and excellent lecture (link) by Jane Woodward, an experienced petroleum geologist, energy entrepreneur, and Adjunct Professor in the Department of Civil and Environmental Engineering at Stanford University. It’s a well spent 76 minutes.
Think of the Earth as an Onion: An often used and easy-to-understand analogy of various layers of the earth is the onion explanation. Hydrocarbon deposits are found between the layers of the onion, called zones – which are typically included in a larger formation of hydrocarbon deposits. Formations and zones can vary in size and composition. Virtually all hydrocarbon deposits are a mixture of rock, gases, and water, and some can be vast oceans while others are more like a simple river network. All are measurable, as every well drilled is identified by a unique number assigned by the American Petroleum Institute (API), and the data compiled and cataloged from all wells – via their API numbers – is encyclopedic in value and information. The API number is where all activity associated with the well – from spud to plug or birth to death – is recorded, cataloged, and maintained by the Federal Government via the US Energy Information Administration (EIA), and with State Governments agencies (via Texas Railroad Commission, Oklahoma Conservation Division, among others). Collected and cataloged data and Information on every well drilled in the United States includes the initial Lease Agreement between the Landowner and initial explorer/operator; the drilling application and permit; detailed wellbore engineering, composition and perforation locations; and first production or flush data. The record is then supplemented over the life of the well with service and maintenance records and permits; monthly production logs or activity; any environmental problems and remediation; tax issues; tax or vendor liens; workover repair applications and permits; any fines and reasons for the fines; government imposed restrictions and reasons; other findings and postings; among a myriad of other information useful for due diligence.
Wellbores are engineered, permitted, and then drilled to pull or extract hydrocarbon minerals from certain zones (link) or from several zones found at certain depths, and equipment is then installed to facilitate the oil and gas extraction (link). The more information that is known about the Formation and Zone, the higher the confidence for petroleum engineers to more accurately forecast expected production; well completion and operating costs; various environmental and financial risks; and ultimately, performance longevity.
Understanding Well Bore Structures and Extraction Methods: as the earth’s core continues to regenerate itself through seismic activity, inherent pressure is created allowing for some wells, for a time, to yield production without requiring much supplemental assistance. Primary recovery is when the natural pressure of the reservoir, or gravity, push oil/water/gas into the wellbore for pumps to then pull the oil/water/gas mix to the service. Depending on the economic cost of doing so, gas is either vented, flared, or captured and sold, while oil is separated and directed into a dedicated storage tank, with the water collected and directed into another tank. Oil tanks are then gauged, emptied of accumulated oil, gauged again, and sold, while water that was collected is injected back into the intrinsic water zone via a dedicated water disposal well. Historically, most wells are vertical wells (link) that are perforated at different depths to align with hydrocarbon zones. However, more recently, almost 80% of all new wells drilled are horizontal wells (link) which allow for greater production yield from a single wellbore in a given zone while minimizing the effect of having multiple drilling sites and pumping equipment scattered over the surface property.
