Water Analytical Data as a Tool in Drilling and Production Economics
Authors: Martin W.C. 
Published: December 2007

This paper reviews when to use water analytical data to supplement engineering evaluations. The paper also discusses preventive and remedial measures for obtaining maximum efficiency at minimum cost. Using data to identify sources of waters in production, drilling, and recovery leads to improved economy and efficiency.

Introduction
During the past 25 years there has been increased need for individuals involved in drilling and producing oil and gas to become more familiar with water technology. Formerly, water was only an undesirable aspect of oil and gas recovery. Although water still affects recovery in the oil field, widespread handling, injection, and disposal of water caused new problems during this era. Currently, individuals engaged in drilling or production must be aware that water analytical data are useful in drilling and recovering oil and gas when thoroughly understood and treated sensitively. Additional application of water technology in the oil field has been accomplished by accumulating massive amounts of knowledge about water during the past 25 years. The engineer who uses this knowledge has an advantage. Although conversion of water analytical data into useful information can be highly complex, a reasonably accurate science has developed. This paper provides those individuals responsible for drilling and producing with enough knowledge so they can use the information derived from analytical data.

Sampling
The most common error in water studies is failure to recognize the importance of the water sample. The value of information derived from analytical data begins with the water sample being studied. The sample must represent the water being studied to be valuable. If a sample is acquired carelessly and is not representative, it can be of limited use, of no use, or even misleading. One of the first things the interpreter should consider is whether the water being studied is actually represented by the sample. Different objectives have different requirements for acquisition of samples. In all cases, samples should represent operating conditions as closely as possible. Table 1 represents some basic requirements in sampling. Where field testing is indicated, it is often advantageous (if not imperative) for the analyst to acquire the samples when establishing sensitive characteristics. Many common misconceptions exist in this regard:bacteria should be identified in the field,hydrogen sulfide should be determined in the field, orpotential scaling conditions should be field tested.
These tests need to be performed the same day the sample is acquired, but more representative results can be obtained under controlled laboratory conditions. Many detrimental and misleading influences exist when a sample is not representative; we cannot include all of them. This paper covers many uses of water analytical data. The reader should remain aware that a representative sample is the most important requirement for basic data.

Analysis Requirements
Types of analysis vary as widely as the information needed. Some analyses can be used with several circumstances. The desired analysis is best obtained by telling the analyst the objective of the analysis. An experienced analyst should know how an analysis should be conducted.
JPT
P. 1342