Problems Related to Squeeze Cementing
- S.H. Shryock (Halliburton Co.) | K.A. Slagle (Halliburton Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- August 1968
- Document Type
- Journal Paper
- 801 - 807
- 1968. Society of Petroleum Engineers
- 2.2.3 Fluid Loss Control, 1.14.3 Cement Formulation (Chemistry, Properties), 1.14 Casing and Cementing, 5.1 Reservoir Characterisation, 5.1.2 Faults and Fracture Characterisation, 5.2.1 Phase Behavior and PVT Measurements, 2.2.2 Perforating, 1.11 Drilling Fluids and Materials, 6.1.5 Human Resources, Competence and Training, 2 Well Completion, 2.4.5 Gravel pack design & evaluation, 1.8 Formation Damage, 5.2 Reservoir Fluid Dynamics, 4.1.3 Dehydration, 4.2.3 Materials and Corrosion, 1.6 Drilling Operations, 3 Production and Well Operations
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Causes of problems relating to squeeze cementing operations are presented. Much has been written on materials and techniques that have been used in particular areas, but little mention is made of some problems that occur during the operation.
Squeeze cementing generally can be described as the process of forcing a cement slurry into holes in the casing and cavities behind the casing. These operations are usually performed during drilling and completion of a well, or for repairing or altering a well at some later date. Squeeze cementing is necessary for many reasons, but probably the most important use is to segregate hydrocarbon producing zones from those formations producing other fluids. The key factor on a squeeze cementing job is that of placing the cement at the desired point or points necessary to accomplish the purpose.
Squeeze cementing problems are closely related to man's ability to understand the earth's properties once its crust has been penetrated. It is often difficult to determine why some wells can be squeezed successfully with one job while others in the same field require four or five jobs. There seem to be a number of opinions as to the proper method of squeeze cementing. We are not attempting to argue or find fault with these opinions; rather we hope to approach and recognize problems that do occur in such a manner that we might learn to consider ways in which to solve them.
Applications of Squeeze Cementing
Some of the most pertinent applications for squeeze cementing that need consideration are: (1) supplementing a primary cementing job that may be deficient because of channeling or insufficient fillup (Fig. 1); (2) reduction or elimination of water intrusion from above or below the hydrocarbon producing zone (Fig. 3); (3) reduction of the GOR by isolating the oil zone from an adjacent gas zone; (4) repair of a casing leak that might have developed due to corrosion, pressure parting or joint leaks (Fig. 2); and (5) abandoning of old perforations or plugging of a depleted or watered-out producing zone.
The language used in squeeze cementing is rather loose and subsequently leaves much to the imagination of those expected to execute the job. During training sessions held by one of the major oil companies the past 2 years, drilling people were presented with the question, "What is your definition of a breakdown?" Recognizing that a majority of those present were from California oil fields, and that the major application for squeeze cementing is that of supplementing a faulty primary job to obtain isolation of an oil zone from adjacent water zones as required by the California Division of Oil and Gas, the type of squeeze job that was foremost in their minds was that of squeezing water-shutoff holes. There were two definitions expressed most frequently:
(1) That pressure necessary to break down or fracture the formation so that it will accept fluid.
(2) That which must he done before one can attempt a squeeze cementing job.
Breakdown actually is a poor name for what really needs to be attained on most squeeze jobs since the prominent problem is in the wellbore, and the desired performance is for the perforations and cavities to accept fluid without fracturing. Fractures normally will accept the cement slurry and often great volumes of it, but not necessarily in the area that needs repair. Obtaining a fracture on the breakdown will more often than not cause extra rig time. require greater volumes of cement, and create lost time waiting on cement-all of which are costly.
A term closely related to breakdown and one that needs to be understood is formation fracture gradient which is the pressure/foot of depth required to create a fracture. Also of interest is the fact that propagation and extension of a fracture usually require a lower pressure than was needed for its creation. Too often it is assumed that overburden lifting is necessary for a fracture to occur. Also, due to average formation density, the fracturing gradient is anticipated to be at least 1 psi/ft of depth. This is a good round number and easy to use in calculations, but experience has indicated that due to structural stresses in the earth and elasticity of the earth's formations, fractures usually occur at less than 1 psi/ft and often as low as 0.6 psi/ ft.
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